•f-  -v^ir  Trt^VT^fc  S~*\Y~*  T    T"7*  f~**  rTpir^  T' 

IYDROEIJECTRI 


Hfiitlfj/Mffi 


DEVELOP 


iff  fli 


UfltW 


E.  &  M    E. 


.DO  NOT  TAKE  FROM    ROOM 


GIFT  OF 

ASSOCIATED  ELECTRICAL   AND 
MECHANICAL   ENGINEERS 


MECHANICS  DEPARTMENT 


Library 


tbe  same  autbor 


STEAM-ELECTRIC 
POWER  PLANTS 


A  Practical  Treatise  on  the  Design  of 
Central  Light  and  Power  Stations  and 
their  Economical  Construction  and  Oper- 
ation. 

11x8  Inch.  473  Pages.  500  Figures 
Net,  $5.00  (See  Last  Page) 


A.E.&M 

HYDROELECTRIC         LUNIV- of  CAI 
DEVELOPMENTS  AND  ENGINEERING 


A    PRACTICAL    AND     THEORETICAL     TREATISE    ON 
THE  DEVELOPMENT,   DESIGN,   CONSTRUCTION, 
EQUIPMENT  AND  OPERATION  OF  HYDRO- 
ELECTRIC TRANSMISSION  PLANTS 


BY 

FRANK    KOESTER 

)i 

CONSULTING   ENGINEER,     ASSOC.    MEM.    AM.  INST.  E.  E. 
MEMBER   SOCIETY   GERMAN    ENGINEERS    (BERLIN),    AUTHOR   OF   "  STEAM -ELECTRIC   POWER   PLANTS1 


WITH  500   ILLUSTRATIONS 


SECOND   EDITION 


NEW   YORK 
D.  VAN    NOSTRAND    COMPANY 

23  MURRAY  AND  27  WARREN  STREETS 

LONDON:    CONSTABLE    &    CO.,    LTD. 
191 1 


DEPT. 

COPYRIGHT,  1909 

BY 
D.  VAN   NOSTRAND   COMPANY 


#7 


Engineering 
Library 


ALSO  ENTERED  AT 

STATIONER'S  HALL  COURT, 

LONDON,  ENGLAND 

All  Right i  Reserved 


To  MY  BROTHERS 

JOHANNES    KOESTER,  CONSULTING  ENGINEER 
KLAGENFURT,  AUSTRIA 

FRITZ   KOESTER,  CHIEF  ENGINEER 
HAMM,  W.,  GERMANY 


7492C2 


PREFACE. 


OWING  to  our  supposedly  inexhaustible  coal  supply,  interest  in  hydraulic  develop- 
ment has  naturally  been  of  tardy  growth  until  recent  years;  and  it  is  only  lately  that 
the  government  has  taken  steps  toward  the  development  and  commercial  use  of 
water  power  resources  and  the  preservation  of  the  forests. 

In  Europe  the  limited  coal  supply  early  induced  the  utilization  of  the  water 
resources;  and  the  various  Continental  governments  encouraged  this  movement  by 
granting  favorable  franchises,  and  in  many  cases  advanced  money  to  finance  the 
undertakings,  at  the  same  time  protecting  the  water-sheds  by  rigid  enforcement  of 
forest  preservation  laws.  It  is  but  natural,  therefore,  that  hydraulic  developments 
and  electric  transmission  received  early  and  special  attention  abroad,  and  as  a  result 
Europe  abounds  in  hydraulic  developments,  utilizing  heads  varying  from  16.5  inches 
to  3116  feet. 

Believing  that  the  progress  in  hydroelectric  engineering  is  stimulated  by  the 
interchange  of  American  and  European  ideas,  and  having  had  considerable  prac- 
tical experience,  both  here  and  abroad,  the  author  presents  this  volume  as  compre- 
hending the  most  advanced  American  and  European  practice,  and  trusts  that  numer- 
ous novel  features  of  hydraulic,  mechanical,  and  electrical  engineering  are  made 
obvious.  To  point  out  a  few  of  the  new  features,  the  following  are  cited:  Air- 
shafts  and  equalizing  chambers  in  connection  with  pressure  tunnels.  Seamless- 
welded,  flangeless,  telescoping  penstocks  to  facilitate  shipment  and  to  eliminate 
expansion  joints.  Siphon  system,  in  contradistinction  to  the  inverted  siphon  - 
which  latter  is  a  misnomer.  Impulse  wheels  with  draft  tubes  and  multiple,  non- 
\rater-wasting  nozzles.  Compound  turbine  on  a  single  shaft,  the  discharge  of  one 
being  the  supply  of  the  other.  Rapid  and  complete  turbine  tests  by  curtain  methods 
and  autographic  recording  device.  Thirty-thousand-volt  generators  and  their 
efficient  protective  devices  against  lightning.  Unique  combination  of  single  and 
three-phase  high-tension  transmission  systems  from  three-phase  generators.  Wagon- 
panel  switchboard  systems.  Segregation  and  decentralization  of  switchboards. 
Continuous  water-flow  grounders  and  horngaps  with  micrometric  setting.  Two- 
legged  transmission  towers  and  line-crossing  protection. 

It  is  not  the  object  of  the  engineer  as  a  designer  of  hydroelectric  developments 
to  design  any  particular  machine,  such  as  a  turbine,  generator,  transformer,  etc., 
but  to  provide,  by  selection  from  the  different  makes,  an  assemblage  of  machines  and 
devices,  each  designed  to  perform  its  particular  function  in  the  most  economical  manner, 
and  to  have  the  machines  properly  combined  to  form  one  complete  unit  for  the  purpose 


viii  PREFACE. 

of  generating  and  transmitting  electrical  current  from  water  power  on  a  satisfactory 
commercial  basis.  Being  of  the  opinion  that  a  good  illustration  may  tell  more  at  a 
glance  than  a  long  discussion,  numerous  cuts  are  presented  to  readily  show  the  present 
standing  of  the  American  and  European  Hydroelectric  Engineering.  Reports,  maps, 
and  charts  on  rainfall,  evaporation,  and  run-off  may  be  directly  acquired  from  the 
various  governments,  and  therefore  are  not  herein  given. 

As  engineers,  students,  and  others  desire  suggestions  and  examples  in  the  same  or 
similar  lines  of  work  as  executed  by  engineers  of  standing,  there  are  given  in 
Part  III  descriptions  of  several  hydroelectric  developments,  distinctive  in  their  indi- 
vidual features.  From  these  the  experiences  and  opinions  of  various  authorities 
and  examples  of  their  works  are  given;  for  instance,  the  Niagara,  Lockport  and 
Ontario  Power  Company's  development  is  an  epitome  of  papers  by  five  authorities. 
The  following  eight  examples  are  chosen  as  representative  plants  of  America  and 
Europe: --The  Ontario  Power  Plant  (medium  head)  and  its  60,000- volt  trans- 
mission system;  The  Great  Falls  Plant  (low  head),  Charlotte,  N.  C.,  with  its  n,ooo 
and  44,ooo-volt  lines,  together  with  data  on  the  fundamental  requirements  regarding 
the  development,  source,  and  market  for  power.  The  Necaxa  Plant,  Mexico,  which 
gives  excellent  examples  of  a  high  head  development,  and  a  i7o-mile,  60,000- volt 
(ultimate  voltage  80,000)  distribution.  In  the  description  of  the  Kykkelsrud-Hafs- 
lund  system  the  parallel  operation  of  two  prominent  Norwegian  low  head  plants 
is  presented.  The  Urfttalsperre  plant  (medium  head),  Germany,  the  most  promi- 
nent of  the  kind  in  Europe,  furnishes  striking  examples  of  how  to  harness  the  yearly 
run-off  and  to  husband  natural  resources  in  low  mountainous  countries.  The  unique 
price  scale  adopted  enables  the  consumer  to  secure  power  as  low  as  0.9  to  i  cent 
per  K.W.  hour.  Another  German  plant,  the  Uppenborn,  embodies  many  novel 
features  in  its  low  head  development  and  5o,ooo-volt  transmission  lines,  and  also 
illustrates  the  effect  of  high  voltage  on  a  telephone  system.  The  Brusio  Plant 
(1300  feet  head)  and  its  5o,ooo-volt  Swiss-Italian  transmission  system,  probably 
surpasses  all  other  hydroelectric  undertakings  because  of  its  many  new  features. 

Some  discussion  has  arisen  among  American  engineers  as  to  the  practicability 
of  direct  generation  of  high  voltages  and  the  consequent  elimination  of  step-up 
transformers.  For  many  years  Continental  Europe  has  had  several  high  voltage 
generator  plants  in  operation,  and  that  in  Manojlovac,  Dalmatia,  is  the  latest  and 
foremost  of  the  kind,  having  four  6ooo-HP.  Francis  turbines  connected  to  30,000- 
volt  generators.  The  current  is  transmitted  over  a  2i-mile  aerial  line,  sufficiently 
protected  against  lightning  by  simple  devices. 

It  is  hoped  that  the  engineer  in  general,  architect,  and  student,  also  the  manu- 
facturer, promoter,  and  financier  will  find  in  the  text  and  illustrations  a  systematic 
and  comprehensive  treatise  on  hydroelectric  plants  from  their  inception  to  the 
delivery  of  power  to  the  substation  and  consumer. 

FRANK   KOESTER. 

NEW  YORK  CITY, 
April,  1909. 


ACKNOWLEDGMENTS. 


THE  author  is  indebted  to  American  Institute  of  Electrical  Engineers  for 
embodied  paper,  by  D.  R.  Scholes,  "Transmission-Line  Towers  and  Economical 
Spans;"  also  to  those  whose  works  have  been  consulted  as  indicated  throughout  the 
volume. 

For  cooperation:  United  States  Geological  Survey;  Ambursen  Hydraulic  Con- 
struction Company;  National  Wood  Pipe  Company;  Excelsior  Wooden  Pipe 
Company;  Wyckoff  Wood  Pipe  Company;  The  Pelton  Water  Wheel  Company; 
J.  P.  Morris  Company;  Allis-Chalmers  Company;  S.  Morgan  Smith  Company;  The 
Dayton  Globe  Iron  Works  Company;  The  James  Leffel  &  Company;  Escher  Wyss 
&  Co.;  J.  M.  Voith,  Maschinenfabrik;  The  Lombard  Governor  Company;  Rep- 
logle  Engineering  Company;  General  Electric  Company;  Westinghouse  Electric 
and  Manufacturing  Company;  Siemens-Schuckert  Werke;  Allgemeine  Elektricitats- 
Gesellschaft;  Ganz  &  Co.;  Brown,  Boveri  &  Co.;  Maschinenfabrik  Oerlikon; 
Elektrizitats-Gesellschaft  Alioth;  Archbold-Brady  Company;  Aermotor  Company; 
The  Locke  Insulator  Manufacturing  Company;  The  R.  Thomas  &  Sons  Company. 

From  the  technical  press:  Engineering  News;  The  Engineering  Record;  Elec- 
trical World;  Electrical  Review  and  Western  Electrician;  Electrical  Railway  Review; 
Power  and  The  Engineer;  Cassier's  Magazine;  Electric  Journal;  The  Electrical 
Age;  Transactions  of  American  Society  of  Civil  Engineers;  Transactions  of  American 
Institute  of  Electrical  Engineers;  Transactions  of  American  Society  of  Mechanical 
Engineers;  Zeitschrift  des  Vereines  deutscher  Ingenieure;  Schweizerische  Bauzeitung; 
Elektrische  Kraftbetriebe  und  Bahnen;  Elektrotechnik  und  Maschinenbau;  Elektro- 
technische  Zeitschrift;  Bulletin  technique  de  la  Suisse;  Journal  le  Genie  Civil. 

For  collaboration  and  courtesies  extended:  V.  C.  Converse,  engineer  in  charge, 
The  Ontario  Power  Company,  Niagara  Falls;  R.  D.  Mershon,  consulting  engineer, 
New  York;  C.  A.  Mees,  engineer  in  charge,  Southern  Power  Company,  Charlotte, 
N.  C.;  Dr.  F.  S.  Pearson,  consulting  engineer,  New  York;  R.  F.  Hay  ward,  general 
manager,  The  Mexican  Light  and  Power  Company,  Mexico;  C.  E.  Parsons,  chief 
engineer,  Hudson  River  Electric  Power  Company,  Albany,  N.  Y.;  P.  P.  Barton, 
general  manager,  Niagara  Falls  Power  Company,  Niagara  Falls,  N.  Y. ;  E.  W.  Cole- 
man,  general  manager,  Great  Northern  Power  Company,  Duluth,  Minn.;  F.  G. 
Sykes,  general  manager,  Portland  Railway  Light  and  Power  Company,  Portland, 
Ore.;  J.  W.  Young,  vice  president,  McCall  Ferry  Power  Company,  McCall  Ferry,  Pa. 

Also  the  assistance  of  C.  B.  Starbird  is  acknowledged  with  due  appreciation. 


TABLE  OF  CONTENTS. 


PART   I. 
THE   TRANSFORMATION  OF  WATER  POWER  INTO  ELECTRICAL  ENERGY. 

CHAPTER    I. 

PROPOSITION.  PAGE 

INVESTIGATION 3 

FOREST  PRESERVATION 4 

HYDRAULICS. 5 

Laws  of  Hydraulics  —  Gross  Horsepower  —  Miner's  Inch  —  Weir  Dam  —  Flow 
of  River  —  Profile  of  River  —  Government  Reports. 

ECONOMY  IN  DEVELOPMENT 15 

Preliminaries  —  Problems  Involved  —  Designing  Staff  —  Drawings  and  Speci- 
fications —  Field  Office. 

CHAPTER    II. 

DAMS. 
GRAVITY  DAMS 19 

Masonry    Dams  —  Reinforced    Concrete    Dams,    Coffer   Dams  —  Crib    Dams  — 

Timber  Dams —  Steel  Frame  Dams —  Earth  Dams. 
MOVABLE  DAMS 32 

Stony  Gate   Dam  —  Butterfly   Dam  —  Bear  Trap — Cylindrical   Dam  —  Needle 

Dam  —  Chanoine  Dam  —  Flashboards. 
FISHWAYS 37 

CHAPTER    III. 

HEADRACE. 

SCHEME 39 

CONDUITS 40 

Cross  Section  of  Conduits  —  Trenches  —  Masonry  Flumes  —  Wooden  Flumes  — 
Protection  of  Flumes  —  Tunnels — Pressure  Tunnels  —  Friction  in  Tunnels  — 
Seepage  in  Tunnels  —  Construction  of  Tunnels  —  Siphon  System. 

RACKS  AND  GATES 47 

Racks  —  Screens  —  Wooden  Sluice  Gates  —  Iron  Sluice  Gates. 

COLLECTING  BASIN 56 

Scheme  —  Sand  Traps  —  Spillways  —  Gate  Valves. 

xi 


xii  TABLE  OF  CONTENTS. 

CHAPTER    IV. 

PENSTOCKS.  PAGE 

STEEL  PENSTOCKS 59 

Penstock  Run  —  Size  of  Penstocks  —  Friction  —  Loss  of  Head  —  Strength  of 
Penstock  —  Construction  of  Steel  Penstocks  —  Flanges  —  Anchors  —  Saddles  — 
Expansion  Joints  —  Safety  Devices — Standpipes — Protection  of  Penstocks 

WOODEN  PENSTOCKS 78 

Adaptability  —  Spacing  of  Bands  —  Friction  —  Durability  —  Cost  —  Construction 
of  Wooden  Penstocks. 

REINFORCED  CONCRETE  PENSTOCKS 86 

Adaptability —  Material  —  Reinforcement  —  Strength  —  Construction. 


CHAPTER    V. 

POWER  PLANT. 

GENERAL  ARRANGEMENT 88 

Forebay  —  Low  Head  Plants — Medium  Head  Plants —  High  Head  Plants. 

EXCAVATION  AND  FOUNDATION , .    .  .  • •  102 

Selection  of  Site  —  Test  Holes  —  Character  of  Soil  —  Bearing  Power  of  Soil  — 
Weight  of  Masonry  —  Wooden  and  Concrete  Piling  —  Test  of  Piles  —  Concrete 
Mat  Construction  —  Foundations  —  Anchor  Bolts  —  Grouting. 

SUPERSTRUCTURE ^-T  .  107 

Architectural     Features  —  Material  —  Walls  —  Floors  —  Roof  —  Doors  —      Win- 
dows —  Stairways  and  Elevators  —  Switchboard   Gallery  —  Crane  —  Heating  — 
Ventilation  —  Lighting  —  Lavatories  —  Conclusions. 

STRUCTURAL  STEEL 122 

Roof  Trusses  —  Columns  —  Column  Bases  —  Floors  —  Expansion  Joints  —  Fiber 
Stresses  —  Character  of  Steel  —  Workmanship  —  Inspection  —  Painting  —  Pre- 
vention of  Electrolysis. 


CHAPTER    VI. 

MECHANICAL  EQUIPMENT. 
TURBINES .    . 129 

Classification  —  Low   Head   Turbines  —  Medium   Head   Turbines  —  High   Head 

Turbines  —  Draft  Tubes. 
REGULATING  DEVICES  .  . 143 

Principle    of    Governors  —  Swiss    Governors  —  Lombard     Governor — Replogle 

Governor —  Pelton  Nozzle  Regulation  —  Accessories  —  Couplings. 
OILING  SYSTEM 1 54 

Oil  Required  —  Filtering  Tanks  —  Oi!  Pumps —  Supply  Tanks  —  Oil  Piping. 
TESTING  TURBINES 157 

European  Methods  —  Holyoke  Tests. 


TABLE  OF  CONTENTS.  xiii 

CHAPTER    VII. 

ELECTRICAL  EQUIPMENT.  PAGE 

GENERATORS 167 

Classification  —  Induction  Generator — Revolving  Field  Generator — Revolving 
Armature  Generator  —  Regulation  —  Efficiency  —  Frequencies  —  Voltage  —  Ex- 
citers —  Generator  Leads  —  High  Voltage  Generators. 

SWITCHING  ROOM : .  .     176 

General  Arrangement. 

SWITCHBOARDS 18 1 

Object  —  Types  —  Panel  Type  —  Pedestal  or  Column  Type  —  Desk  or  Panel 
Board  —  Direct  Current  Board  —  Low  Tension  A.  C.  Boards  —  Wagon  Panel  — 
High  Tension  A.  C.  Boards. 

SWITCHBOARD  EQUIPMENT 191 

Volt  and  Ammeters  —  Wattmeters  —  Synchronizing — Power  Factor  Meter  — 
Frequency  Meter  —  Rheostats  —  Illumination  of  Switchboards. 

WIRING  DIAGRAMS : 194 

System  of  Wiring  Diagrams  —  American  and  European  Systems. 

Bus  BARS  .  201 

• 

Size  of  Bus  Bars  —  Closed  Compartments  —  Open  Compartments. 

OIL  SWITCHES 204 

General  Remarks  —  Types  of  Oil  Switches  —  Circuit  Breakers  —  Overload  Relays 
—  Reverse  Current  Relays  —  Overload  Voltage  Relays. 


PART  II. 
THE  TRANSMISSION  OF  HIGH  TENSION  ELECTRICAL  CURRENT. 

CHAPTER    VIII.       . 

ELECTRICAL  TRANSMISSION. 

/ 

GENERAL  REMARKS  215 

TRANSMISSION  CONDUCTORS 215 

Strength  of  Conductors  —  Elasticity  of  Conductors  —  Cables  as  Conductors  — 
Spacing  of  Conductors  —  Characteristics  of  Conductors  —  Size  of  Conductors  — 
D.  C.  Conductors —  D.  C.  Problem  —  A.  C.  Conductor — A.  C.  Problem  —  Trans- 
position —  Corona  Effect. 

POLE  AND  TOWER  CONSTRUCTION 228 

WOODEN  AND  CONCRETE  POLES 228 

Wooden  Poles  —  Strength  of  Wooden  Poles  —  Kind  of  Wood  —  Cross  Arms  — 
Life  of  Wooden  Poles  —  Preservation  of  Wooden  Poles  —  Pole  Line  Construction' 
—  Guys  —  Concreted  Wooden  Poles  —  Reinforced  Concrete  Poles  —  Steel  Pipe 
Towers. 


xiv  TABLE  OF  CONTENTS. 

PAGE 

REINFORCED  CONCRETE  TOWERS 234 

STEEL  TOWERS 235 

Wind  Pressure  on  Structure  —  Wind  Pressure  on  Conductors — Sleet — Founda- 
tions —  Portability  —  Two  Leg  Towers  —  Three  Leg  Towers  —  Four  Leg  Towers 
—  Tretzo  Tower — Syracuse  Tower — Oneida  Tower  and  Specification  —  New 
York  Central  Tower — Lucerne  Tower — Brusio  Tower — Suspended  Insulator 
Tower  —  Line  Stresses  —  Transmission  Line  Towers  and  Economical  Spans. 

INSULATORS 265 

Pin  Insulators  —  Suspension  Insulators  —  Strain  Insulators  —  Insulator  Pins  — 
Method  of  Tying  Conductors  —  Section  Switches  —  Wall  Outlets. 


CHAPTER    IX. 

SUBSTATIONS. 

GENERAL  ARRANGEMENT 280 

Location  of  Substations  —  Size  of  Units  —  Arrangement  of  Substations  —  Ventila- 
tion —  Drainage  —  Air-Compressor. 

TRANSFORMERS 286 

Type  of  Transformers  —  Characteristics  of  Transformers  —  Regulation  of  Trans- 
formers—  Efficiency  of  Transformers — Connections — Delta  vs.  "Y"  Connec- 
tions —  Oil-cooled  Transformers  —  Forced  Oil-cooled  Transformers  —  Air-cooled 
Transformers. 

CONVERTERS 296 

Voltage  and  Frequency  —  Phases  —  Field   Connections  —  Starting  of  Converters 
—  Hunting —  Induction  Regulator —  Compounding —  Reactances. 

MOTOR-GENERATORS 302 

FREQUENCY  CHANGERS 303 

SWITCH  GEAR  OF  SUBSTATIONS 307 


CHAPTER    X. 

LINE  PROTECTION. 

LIGHTNING  ARRESTERS 309 

Purpose  —  Lightning  Discharge  —  Principles  of  Arresters  —  Horn  Lightning 
Arresters  —  Horn-gap  Setting  —  Choke  Coils  —  Multigap  Arresters  —  Action  of 
Multigap  Arresters  —  Insulation  of  Multigap  Arresters  —  Fluid  Arresters  —  Loca- 
tion of  Lightning  Arresters. 


TABLE  OF  CONTENTS. 


XV 


PART  III.     (Appendix.} 


MODERN   AMERICAN   AND   EUROPEAN    HYDROELECTRIC    DEVELOPMENTS. 

PAGE 

POWER  PLANT  OF  THE  ONTARIO  POWER  COMPANY,  AND  THE  TRANSMISSION  SYSTEM  OF 
THE  NIAGARA,  LOCKPORT  AND  ONTARIO  POWER  COMPANY 327 

POWER  PLANT  OF  THE  SOUTHERN  POWER  COMPANY,  NORTH  CAROLINA,  AND  ITS  TRANS- 
MISSION SYSTEM 348 

POWER  PLANT  OF  THE  MEXICO  LIGHT  AND  POWER  COMPANY,  NECAXA,  AND  ITS  TRANS- 
MISSION SYSTEM 369 

POWER  PLANT  OF  THE  AKTIESELSKABET  GLOMMENS  TRAESLIBERI,  CHRISTIANA,  AND 
ITS  TRANSMISSION  SYSTEM 382 

THE  URFTTALSPERRE  POWER  PLANT  AT  HEIMBACH  OF  THE  RURTALSPERREN-GESELL- 
SCHAFT,  AACHEN,  GERMANY,  AND  ITS  TRANSMISSION  SYSTEM 393 

THE  UPPENBORN  PLANT  AT  MOOSBURG  OF  THE  STADTISCHEN  ELEKTRIZITATSWERKE, 
MUNICH,  GERMANY,  AND  ITS  TRANSMISSION  SYSTEM  .  .  . 403 

POWER  PLANT  OF  THE  AKTIENGESELLSCHAFT  KRAFTWERKE  BRUSIO,  SWITZERLAND, 
AND  THE  TRANSMISSION  SYSTEM  OF  THE  SOCIETA  LOMBARDA  PER  DISTRIBUZIONE 
DI  ENERGIA  ELETTRICA,  ITALY 417 

THIRTY  THOUSAND  GENERATOR  VOLTAGE  PLANT,  AND  TRANSMISSION  SYSTEM  OF  THE 
SOCIETA  PER  LA  UTILIZZAZIONE  DELLE  FORZE  IDRAULICHE  BELLA  DALMAZIA, 
AUSTRO-HUNGARY  435 

INDEX 445 


LIST    OF    ILLUSTRATIONS. 


HYDRAULIC  MEASURING  DEVICE. 

PAGE 

Weirs 8 

Current  Meter 1 1 

Plotting  Curves  for  River  Discharge 12 

Plotting  Curves  for  River  Beds 13 

Automatic  Graphical  Registrator 1 58 

Curtain  Carriage  Tests 159 

Flume  Tests,  Holyoke,  Mass 160 


DAMS. 

Design  of  Dams .  19,  20,  21 

Concrete  Dams 22 

Cyclopean  Masonry  Dam 22 

Behavior  of  Resultants  in  Solid  Dams 24 

Behavoir  of  Resultants  in  Concrete  Steel  Dams 24 

Reinforced  Concrete  Dams 25 

Submerged  Power  House,  Patapco 25 

Bar  Harbor  Plant,  Ellsworth,  Maine 27 

Reinforced  Concrete  Dam,  Ellsworth,  Maine ^ 28 

Coffer  Dams 29 

Timber  Dams 29 

Steel  Frame  Dams,  Hauser  Lake 30 

Earth  Dams,  Necaxa,  Mexico 31 

Earth  Dam  with  Concrete  Core,  Dixville,  N.  H 32 

Stoney  Roller  Sluice  Gate  Dam 33, 34 

Butterfly  Dam,  Chicago 35 

Fishways , 37 

Dam  and  Penstock,  Necaxa 373 

Dam,  Heimbach 393 , 394 

HEADRACE. 

Typical  Headrace 39 

Timber  Flume 43,  44 

Tunnel  and  Overflow 46 

Lake  Poschiava  Siphon 47 

xvii 


xviii  LIST  OF  ILLUSTRATIONS. 

PAGE 

Screen  House,  Niagara  Falls  Power  Company 48 

Racks  and  Deflector,  Hafslund,  Norway 49 

Screens 50,  5 1 

Vent .  .  ^ 50 

Penstock  Inlet 50 

Wooden  Sluice  Gate 52 

Drum  Gate 54,  55 

Cylindrical  Gate 56 

Niagara  Power  Developments 328,  329 

Intake  of  Forebay,  Ontario 330 

Screen  House,  Ontario 330 

Gate  House,  Ontario 331 

Map  of  Power  Development,  Charlotte,  N.  C 350 

Necaxa  Power  Development ; 370 

Headrace,  Kykkelsrud 387 

Gate  House  and  Penstock,  Brusio 421 


PENSTOCKS. 

Flanges 66,  67,  68,  69,  70,  72 

Penstock,  Anchor 70 

Hinged  Penstock  Support 71 

Expansion  Slip  Joints 71 

Expansion  Flange  Joint 72 

Wedge  Shaped  Expansion  Joint 73 

Penstock  Run,  Loch  Leven,  Scotland 73 

Collecting  Basin 74 

Penstock  Arrangement,  Brusio 74 

Penstock  Vent 74 

Automatic  Flap  for  Penstocks — 75 

Vacuum  Relief  Valve 77 

Automatic  Low  Water  Valve 78 

Wooden  Stave  Penstock 79,  80 

Detail  of  Wooden  Stave  Penstock 82 

Penstock  Partly  Embedded,  Ontario 331 

Penstock  Intake,  Necaxa 371 


POWER   PLANTS. 

Chevres,  France 54 

Lyon,  France 56 

Georgia,  Albany 89 

Holyoke,  Mass 89 

Winnipeg,  Manitoba ' 89 

Colliersville,  Oswego,  N.  Y 90,  91 

Shawinigan,  Can 92 


LIST  OF  ILLUSTRATIONS. 


A.E.&M.E 


xix 


92,  94 


McCall  Ferry,  Pa 

Niagara  Falls  Power  Company 7T  95,  107,  109 

Toronto,  Can 96,  97 

Kern  River,  Plant  No.  i 97,  99 

Snoqualmie  Falls 100 

Kykkelsrud,  Norway 102 

Wooden  and  Concrete  Piles 105 

Stuttgart,  Germany no 

Obermatt,  Lucerne,  Switzerland 112 

Urfttalsperre,  Germany 113 

Geneva,  Switzerland 114 

Sillwerke,  Tyrol 1 20 

Tivoli,  Rome,  Italy 121 

Typical  Roof  Trusses 122 

Typical  Columns 123 

Crane  Column 124 

Ontario  Power  Plant  and  Distributing  Station 333~33^ 

Charlotte,  N.  C 351,  356 

Necaxa,  Mexico 374~377 

Kykkelsrud,  Norway 383-388 

Heimbach,  Germany 395,  396 

Uppenborn,  Germany 404,  405 

Brusio  Power  Plant  and  Penstock  Run,  Italy 418,  422,  424 

Manojlovac  Power  Plant,  Dalmatia 436-438 


MECHANICAL  EQUIPMENT  OF  POWER   PLANTS. 

American  Turbine 130 

American  Turbine,  Runner,  and  Gate 131 

Low  Head  Turbines 132 

Vertical  Shaft  Francis  Turbine 133 

Double  Spiral  Francis  Turbine* .' 134 

Compound  Francis  Turbine 135 

Double  Flow  Francis  Turbine 136 

Thrust  Bearing 137 

Impulse  Wheel  and  Nozzles 138,  139 

Francis  Spiral  Turbine,  Horizontal  Shaft 140 

9700  H.P.  Francis  Turbine 142 

Impulse  Wheel  Nozzle  and  Regulator 144 

Spoon  Wheel  Turbine  and  Governor 145 

Turbine  Gate 146 

Governors 147,  149,  150 

Hydraulic  Relief  Valves 148 

Pressure  Regulator 150 

Pelton  Wheel  Buckets 151 

Automatic  Deflecting  Nozzle 152 


CM 


xx  LIST  OF  ILLUSTRATIONS. 

PAGE 

Relief  Valves 153 

Flexible  Coupling  . 153 

Oil  Filters. ...  154,  155 

Oil  Filter  for  Large  Capacities 155 

6ooo-Horsepower  Francis  Turbine 439 


ELECTRICAL  EQUIPMENT   OF   POWER   PLANTS. 

Generator,  Two-Phase,  Umbrella  Type  168 

Induction  Generator 168 

Flywheel  Type  Generator 169 

Three-Phase  Generators 171 

Exciters 171 

Three-Phase  Generator 172 

Characteristic  Curves  of  Generator  .  . 172 

Switch  and  Transformer  Room,  Obermatt 177 

Switch  House,  Castelnuovo-Valdarno,  Italy 178 

Shawinigan  Falls  Plant 179 

Puget  Sound  Plant 180 

Switchboard,  A.  C.  and  D.  C.,  Necaxa  Plant,  Mexico 181 

Switchboard,  Panel  and  Bench  Desk 182 

Instrument  Columns 183 

Switchboard  Panel,  Rear  View,  Obermatt 184 

Remote  Control  Switches 185 

Instrument  Bench  Desk 186 

Switchboard  Panel,  D.  C 186 

Switchboard,  Combined  Panel,  D.  C 187 

Switchboard  for  Three-Phase  Generator 188 

Switchboard,  Wagon  Panel 189 

Oil  Switch  and  Bus  Bar  Compartment 190 

Wattmeter  Connections 192 

Motor  Controlled  Rheostat 193 

Remote  Hand  Operated  Rheostat 194 

Wiring  Diagram,  Valdarno 195 

Wiring  Diagram,  Ontario 196 

Wiring  Diagram,  Necaxa 197 

Wiring  Diagram  for  Exciters 198 

Wiring  Diagram,  Urfttalsperre 199 

Wiring  Diagram,  Obermatt 200 

Wiring  Diagram  for  Single  Generator  and  Step-up  Transformer 201 

Circuit  Breaker  and  Bus  Bar  Compartments 202 

Open  Bus  Bar  Compartments,  Lontsch,  and  Luzerne  Plants 203 

Solenoid  Controlled  30,ooo-volt  Oil  Switch 205 

io,ooo-volt  Air  Break  Switch 205 

i i,ooo-volt  Oil  Switch,  Solenoid  Controlled 206 

6o,ooo-volt  Oil  Switch  Compartment,  Ontario 207 

3o,ooo-volt,  Motor  Controlled  Oil  Switch 208 


LIST  OF  ILLUSTRATIONS.  xxi 

PAGE 

1 1,000  and  5o,ooo-volt  Oil  Switch,  Castellanza,  Italy 209 

88,ooo-volt  Circuit  Breakers 210 

35,ooo-volt  Switch  with  Current  Blowouts 210 

High  Tension  Time  Relay 210 

Control  Room,  Ontario 337 

High  Tension  Bus  Bars,  Ontario 340 

Oil  Pipe  System  for  Transformers,  Charlotte,  N.  C 354 

Interior  of  Generating  Room,  Charlotte,  N.  C 357 

Wiring  Diagram,  Charlotte  Plant 358 

High  Tension  Switch  Room,  Charlotte,  N.  C 359 

Solenoid  Operated  Oil  Switch 360 

Switch  Room,  Kykkelsrud 389 

Generators  and  Exciters,  Heimbach 397 

Bus  Bar  and  Switch  Room,  Heimbach 400 

Switchboard,  Heimbach 398 

Generating  Room,  Uppenborn 406 

Wagon  Panel,  Siemens-Schuckert,  Uppenborn 414 

Switchboard,  Individual  Generator,  Brusio 425 

Switchboard,  Rear  View,  Brusio 427 

Bus  Bars,  Brusio 427 

Exciter  Switchboard,  Brusio 427 

3o,ooo-volt  Generator 439 

HIGH  TENSION  TRANSMISSION. 

Wooden  Poles  for  5o,ooo-volt  Transmission , 228,  229 

"  A  "  Frame  Tower,  6o,ooo-volt 230 

Cross  Arm  and  Guard  Wire,  4o,ooo-volt 231 

Reinforced  Concrete  Tower 234 

Two-Legged  Steel  Tower,  37  feet 237 

Types  of  Poles  and  Towers,  5o,ooo-volt 238 

Four-Legged  Twin  Steel  Tower 239 

Steel  Tower,  45  feet,  Syracuse 240 

Steel  Towers,  Niagara  Crossing 241 

Dead  End  Steel  Towers,  Rochester 242 

Steel  Tower,  Standard,  New  York  Central 245 

Tower,  Bracket  and  Guard,  35,ooo-volt,  Heimbach 246 

Cantilever  and  Steel  Tower,  27,ooo-volt,  Obermatt 246 

Steel  Tower,  5o,ooo-volt,  Piattamala 247 

Highway  Crossing,  5o,ooo-volt,  Lecco 248 

Steel  Towers,  i  io,ooo-volt,  Muskegon 249 

Steel  Tower,  Suspended  Insulator  Type 250 

Steel  Towers,  Diagrams  of  Different  Types 253,  256,  259 

Chart  for  Economical  Width  of  Tower  Base 259 

Chart  for  Economical  Span 261 

Type  of  Foundation 263 

Chart  for  Sag  of  Conductors 264 


xxii  LIST  OF  ILLUSTRATIONS. 

PAGE 

Insulator,  4o,ooo-volt,  Kern  River 265 

Insulator,  5o,ooo-volt,  Taylor's  Falls 265 

Insulator,  40,000  to  5o,ooo-volt,  Paderno 268 

Insulators,  Methods  of  Suspending 269 

Insulators,  Suspended 268,  270 

Insulator,  Suspended  no,ooo-volt,  Muskegon 270 

Application  of  Strain  Insulators 271 

Anchor  Insulator 271 

Rolling  Insulating  for  Long  Spans,  Tofwehult 271 

Insulator  Pin,  Porcelain  Base 272 

Insulator  Pin,  all  Steel 272 

Insulator  Pin,  Detail,  6o,ooo-volt 273 

Insulator  Tie  and  Clamp,  6o,ooo-volt,  Ontario 273 

Insulators,  6o,ooo-volt,  Ontario 273 

Line  Disconnecting  Switch 275 

Two  Break  Section  Switch 276 

Typical  Wall  Outlets 276-277 

Cross  Arm  Guard  Wire,  Lightning  Rod 323 

Transmission  Line,  62,ooo-volt,  Ontario 341 

Niagara  Crossing 342 

Cantilever,  Niagara  Crossing 343 

Cross  Connection  and  Open  Air  Fuse,  Auburn 343 

Four  Leg  Tower  on  "Floating"  Foundation,  Montezuma  Swamp 344 

Transmission  System,  Charlotte,  N.  C 349 

Transmission  Feeders 361 

Main  Transmission  Line,  Charlotte,  N.  C 363 

Insulator,  5o,ooo-volt,  Charlotte,  N.  C, 364 

Transmission  Line  in  Cities,  Charlotte,  N.  C 365 

Map  of  Transmission  Line,  Necaxa 378 

Transmission  Tower,  Necaxa 379 

Transmission  Line,  Necaxa 380 

Transmission  Line,  5o,ooo-volt,  Kykkelsrud  to  Hafslund 392 

Wall  Outlet,  Uppenborn 408 

Insulators,  5o,ooo-volt,  Uppenborn 410 

Cable  Tunnel,  Brusio,  Piattamala 427 

Line  Crossing,  5o,ooo-volt,  Piattamala 43 1 

Insulator,  3O,ooo-volt,  Manojlovac 441 

Transmission  Line  Crossing,  Manojlovac 442 


SUBSTATIONS   AND   EQUIPMENT. 

Duluth  Substation • no 

Stansstad  Substation 115 

Substation,  Waterbury 281-282 

Substation,  Typical  Three-Phase 283-284 

Substation,  Steghof,  Switch  Gear 285 

Transformer,  Shell  Type 286 


LIST  OF  ILLUSTRATIONS.  xxiii 

PAGE 

Transformer,  Core  Type 286 

Transformer,  Water  Circulated,  Oil  Cooled 287 

Chart  Showing  Efficiency  of  Air  Blast  Transformer 288,  289 

Transformer  Connections  to  Rotary  Converters 291 

Transformer,  Forced  Air  Circulation 292 

Transformer,  Air  Cooled 293 

Transformer,  Method  of  Water  Cooling,  Molinar,  Spain 293 

Transformers,  Arrangement  of  Air  Blast .  .  - 294 

Transformer,  Chart  Showing  Air  Required 295 

Rotary  Converter,  Substation,  Albina 297 

Automatic  Regulators,  Transformer 300 

Typical  Continental  Motor  Generator,  Substation 302 

Motor  Generator,  Substation,  Steghof 303 

Frequency  Changers 304 

Typical  Switchboard  Panels  for  Substations 305 

Wiring  Diagram,  Waterbury  Substation 306 

Distributing  Station  and  Power  House,  Ontario 333 

Control  Room,  Ontario 337 

Distributing  Station,  Ontario 337 

Transformer  Compartment 338 

High  Tension  Bus  Bars,  Ontario 340 

6o,ooo-volt  Open  Air  Bus  Bars,  Lockport 346 

6o,ooo-volt  Circuit  Breaker,  Lockport 347 

Transformer  Room,  Charlotte,  N.  C '. . . . .  354 

Substation,  El  Oro 381 

Transformer  Room,  Kykkelsrud \ 390 

Substation  Interior,  Hafslund 391 

Transformer  Room,  Heimbach 399 

Transformer  House,  Typical 402 

Transformer  and  Lightning  Arrester  House,  Hirschau,  Uppenborn 411 

Transformer  Water  Flow  Grounder,  Hirschau,  Uppenborn 413 

Horn  Gaps,  Substation,  Hirschau,  Uppenborn 415 

Transformer  Station,  Piattamala 428 

Switch  Room,  Piattamala 429 

Air  Cooled  Transformer,  Open  Type,  Lomazzo 433 

Switch  Room,  Lomazzo 433 

LIGHTNING   ARRESTERS. 

Horn  Gaps,  Showing  Principle  of  Action   310 

Horn  Gaps,  Application  with  Oil  Rheostat 312 

Horn  Gaps,  Construction 313 

Horn  Gaps,  Setting 313 

Lightning  Arrester  Equipment,  Hirschau,  Uppenborn 413 

Protection  of  Overhead  and  Underground  Lines 313 

Water-Flow  Grounder  413 

Station  Protection,  Torchio 314 


xxiv  LIST  OF  ILLUSTRATIONS. 

PAGE 

Protection,  3ooo-volt  Circuit,  Gola 314 

Multigap  Arresters 315,316 

Aluminum  Arrester 318,  319 

Electrolytic  Arresters 320-32 1 

Horn  Gaps,  Water-Flow  Grounder,  Steghof 321 

Water-Flow  Grounders 321-322 

Bank  of  Horn  Gaps,  Choke  Coils,  and  Water-Flow  Grounders,  Vandoise 322 

Water-Flow  Grounders,  5o,ooo-volt,  Piattamala 322 

Lightning  Rod  and  Guard  Wire 323 

Lightning  Protecting  Device,  Heimbach 401 


LIST    OF    TABLES. 


PAGE 

DISCHARGE  OF  WEIRS 9 

VELOCITY  OF  WATER  IN  CHANNELS 42 

PROPERTIES  OF  TIMBER 53 

TESTS  OF  AMERICAN  WOODS 53 

AREA  OF  CIRCLES 60 

FRICTIONAL  HEAD  Loss  IN  PENSTOCKS 62 

CAPACITY  DISCHARGE  OF  PIPES 63 

RIVETED  PIPES 65 

SAFE  STRAIN  OF  PENSTOCK  BENDS 79 

STRENGTH  OF  DOUGLASS  FLR 81 

COST  OF  RIVETED  PENSTOCK 82 

COMPARATIVE  COST  OF  PENSTOCKS 83 

BEARING  POWER  OF  SOIL 103 

WEIGHT  OF  MASONRY 104 

RADIATING  SURFACE  FOR  HEATING 117 

COMPARATIVE  TESTS  OF  TURBINE 161 

MODULUS  OF  ELASTICITY  OF  CONDUCTORS 216 

COEFFICIENT  OF  EXPANSION 216 

STRAND  FACTOR  OF  CONDUCTORS 216 

COMPARISON  OF  WIRE  GAUGES 218 

SOLID  COPPER  WIRE 219 

STRANDED  COPPER  WIRE 220 

REACTANCE  OF  VOLTS 221 

WEIGHT  AND  STRENGTH  OF  WIRES 221 

AMERICAN  AND  ENGLISH  COPPER  CABLE 222 

AMERICAN  AND  ENGLISH  COPPER  WIRE 223 

CORRECTED  WIND  VELOCITIES 235 

COMPARATIVE  TESTS  OF  TRANSMISSION  TOWERS  .    238 

TENSILE  STRENGTH  IN  CONDUCTIVITY  OF  CONDUCTORS 250 

SAG  OF  WIRES  AT  DIFFERENT  TEMPERATURES 252 

RESULTANT  FORCE  IN  TRANSMISSION  TOWERS 262 

AIR  REQUIRED  FOR  TRANSFORMERS 294 

AIR  REQUIRED  FOR  TRANSFORMERS  OF  25  AND  60  CYCLES 295 

SPACING  BETWEEN  MULTIGAP  ARRESTERS 312 

EFFICIENCY  OF  TURBINES 352 

EFFICIENCY  OF  GENERATORS 355 

EFFICIENCY  OF  EXCITERS 355 

EFFICIENCY  OF  TRANSFORMERS 359 

COST  OF  HYDROELECTRIC  INSTALLATION 416 

XXV 


PART  I. 

THE  TRANSFORMATION   OF   WATER   POWER   INTO 
ELECTRICAL   ENERGY. 


HYDROELECTRIC    DEVELOPMENTS   AND 
ENGINEERING. 


CHAPTER    I. 
PROPOSITION. 

Investigation.  Before  developing  a  water  power  much  preliminary  study  is 
necessary  to  ascertain  whether  the  proposition  will  be  a  paying  one.  Reliable  data 
must  be  collected  and  put  in  complete  and  definite  form  before  capitalists  can  be 
interested. 

After  the  investigations  are  made  showing  the  amount  of  energy  available,  the 
possible  field  of  consumption  must  be  carefully  considered.  This  may  include 
other  central  stations,  either  steam,  gas,  or  even  other  water-power  plants.  While 
the  selling  price  of  current  is  known,  it  might  appear  difficult  to  ascertain  what  it 
costs  existing  companies  to  produce  electrical  energy.  There  are,  however,  several 
ways  by  which  this  information  can  be  obtained,  and  with  the  help  of  an  experienced 
engineer  very  close  figures  can  be  ascertained. 

These  costs  are  essential  as  a  guide  for  the  new  development,  because  it  may 
have  to  compete  with  or  possibly  sell  current  to  established  stations,  and  in  any 
event  this  is  the.  salient  factor  in  determining  whether  the  proposed  plant  is  an  advis- 
able development. 

In  the  case  of  selling  power  to  established  electrical  systems  the  plants  are  cus- 
tomarily operated  in  parallel.  In  some  instances  the  separate  companies  have 
found  it  expedient  to  merge  their  interests  and  form  a  corporation.  Having  arrived 
at  the  competitor's  figures,  the  other  prospective  fields  for  current  consumption  must 
be  thoroughly  canvassed,  to  ascertain  the  load  and  the  price  for  which  the  current 
can  be  sold.  In  fixing  the  selling  price  different  rates  are  charged  according  to  the 
amount,  duration,  and  time  of  load.  Conclusions  as  to  the  cost  of  current  can 
only  be  derived  after  trial  load-curves  have  been  plotted,  and  the  careful  balancing 
of  the  engineering  and  commercial  items  for  each  particular  plant. 

Plants  are  economical  in  first  cost  and  in  operation  in  proportion  to  the  constancy 
of  their  load  factors.  With  greatly  varying  loads  much  machinery  is  idle  a  large 
part  of  the  time.  However, 'in  competing  successfully  with  existing  central  station 
or  private  plants,  prospective  consumers  who  will  require  current  for  only  a  few 
hours  each  day  or  possibly  each  week,  and  those  who  will  need  emergency  current, 
must  not  be  overlooked.  That  these  consumers  pay  a  high  rate  for  the  service 
rendered  is  but  natural. 

3 


4  HYDROELECTRIC    DEVELOPMENTS    AND    ENGINEERING. 

After  the  foregoing  investigations  have  been  made,  and  the  figures  show  that  the 
installation  .is  warranted,  the  possible  future  growth  of  the  locality,  such  as  the 
industrial  increase,  electric  railroading,  etc.,  must  be  well  considered;  with  the  growth 
of  the  cornm-anity  an  increase  in  consumers  naturally  follows. 

Hydroelectric  plants  have  often  been  installed  without  provision  for  future 
extension;  the  dams  are  located  in  such  sections  of  the  rivers,  and  are  of  such  a 
design,  that  an  increase  in  storage  supply  or  additional  head  is  impossible.  Plants 
have  also  frequently  been  installed  where  sufficient  water  to  carry  the  full  load 
cannot  be  obtained  during  certain  seasons  of  the  year.  While  the  former  may  be 
due  to  lack  of  foresight,  the  latter  is  attributable  to  negligence  in  proper  investiga- 
tion. Under  such  conditions  competition  would  be  difficult.  In  many  cases  water- 
power  plants  do  not  have  to  meet  competition,  as  they  may  be  pioneers  in  the  field. 
Under  favorable  conditions  the  hydraulic  plant  may  be  reinforced  with  a  steam  or  a 
gas  engine  plant,  this  auxiliary  equipment  taking  the  load  during  periods  of  low 
water  and  hours  of  heaviest  demand. 

The  equipment  and  size  of  the  units  should  be  such  that  they  will  run  at  their 
best  efficiency  throughout  the  day,  that  is,  they  must  not  run  underloaded  or  greatly 
overloaded.  Reserve  units  must  be  kept  in  readiness  to  be  thrown  on  the  line 
when  the  demand  calls  for  them. 

Present  practice  is  to  install  as  large  units  as  possible. 

FOREST   PRESERVATION. 

The  relation  of  forests  to  water-power  development  is  of  the  greatest  impor- 
tance. It  is  a  well-known  fact  that  the  soil  of  forests  retains  the  water  of  precipita- 
tion more  uniformly  and  releases  it  gradually,  so  that  during  dry  seasons  a  supply 
of  water  is  assured.  Flat  non-forested  land  may  hold  the  water  and  form  swamps, 
but  in  most  cases  the  water  drains  off  rapidly,  so  that  streams  having  denuded 
watersheds  are  subject  either  to  floods  or  droughts. 

Long  observation  and  costly  experiments  have  proven  that  forests  receive  a 
greater  quantity  of  rain,  hail,  and  snow  than  land  in  the  same  vicinity.  Mountain- 
ous countries,  whether  bare  or  covered  with  forest,  receive  more  rain  than  flat  coun- 
try; and  the  forests  in  mountainous  countries  receive  more  rain  than  bare  land  at 
the  same  elevation. 

The  following  data  throw  some  light  on  the  effect  forests  have  on  water-power 
developments. 

According  to  the  report  by  the  Swiss  engineer,  Lauterberg,  the  drainage  of  the 
canton  Tessin,  between  1834  and  1862,  was  reduced  about  28  per  cent,  due  to  the 
removal  of  forests.  He  states  further  that  prior  to  the  destruction  of  forests 
the  valleys  were  flooded,  on  the  average,  every  54  months,  while  after  the  forests 
were  destroyed  floods  occurred  every  29  months.  Professor  Ebermeyer  states  that, 
considering  the  evaporating  factor  of  free  land  as  100  per  cent,  the  evaporation  of 
the  forest  land  is  only  22  per  cent,  other  conditions  remaining  the  same.  Dr.  van 
Bebber  observed  that  a  forest  at  an  elevation  of  1000  meters  (3280  feet)  has  about 


PROPOSITION.  5 

50  per  cent  more  drainage  than  free  land  situated  on  the  same  elevation.  Relative 
to  this,  Professor  Schreiber,  who  observed  conditions  in  Saxony,  came  to  the  con- 
clusion that  forests  on  open  country  receive  as  much  precipitation  as  free  land  ele- 
vated 200  meters  (656  feet)  higher.  Further,  Professor  Landolt,  Zurich,  states 
that  for  every  100  meters  (328  feet)  elevation  the  annual  drainage  will  increase 
10  inches. 

Between  the  years  of  1843-1883  the  Ekaterinoslaw  government,  Russia,  culti- 
vated a  forest  of  5000  acres,  and  established  two  meteorological  stations  in  this  sec- 
tion. The  reports  show  that  since  the  Introduction  of  the  forest,  showers  are  much 
more  frequent,  and  the  previously  feared  dry  seasons  are  things  of  the  past.  The 
stations  report  that  the  average  rainfall  between  1893-1897  was  18  inches  for  free 
land,  while  for  the  forests  22.25  inches. 

The  French  government  spent  14,500,000  francs  between  the  years  1861  and 
1877  to  forestize  235,000  acres  in  mountainous  localities.  The  result  was  so  bene- 
ficial that  the  government  decided  to  forestize  about  two  million  acres  additional, 
which  will  probably  cover  60  to  80  years  and  consume  150,000,000  francs.  Austria 
has  at  present  very  elaborate  plans  to  reestablish  forests  in  denuded  sections.  The 
Italian  government  has  set  aside  $8,000,000  as  a  beginning  towards  the  reestablish- 
ment  of  the  forests  in  the  southern  Alps.  For  many  years  Germany  has  enforced 
rigid  laws  for  the  preservation  of  her  forests,  and  in  recent  years  has  encouraged 
and  assisted  water-power  developments. 

In  May,  1908,  the  governors  of  several  States  discussed  the  preservation  of  our 
national  resources,  particularly  those  of  forests  and  water  supply.  This  was  due 
chiefly  to  the  increase  in  the  fluctuation  of  streams,  which  is  a  direct  result  of  the 
destruction  of  forests. 

Fluctuations  of  water  supply  and  danger  due  to  floods  have  forced  water-power 
developments  to  additional  expenditure  to  harness  water  of  uncertain  quantities. 
For  instance,1  one  of  the  largest  power  companies  had  to  build  new  dams  25  per 
cent  greater  in  cross  section  than  the  older  ones  on  the  same  stream;  other  hydraulic 
plants  that  previously  had  abundant  water  are  now  forced  to  supplement  with  auxil- 
iary steam  plants. 

HYDRAULICS. 

Laws  of  Hydraulics.  In  1830,  Galileo  stated  that  the  laws  governing  the  flow 
of  water  were  not  as  well  known  as  those  governing  the  movements  of  the  celestial 
bodies,  and  even  to-day  this  is  still  true.  Our  experimental  data  of  to-day  are  far 
in  advance  of  hydraulic  theory,  hydraulic  engineering  being  based  more  on  empir- 
ical facts  than  on  rational  mathematical  formulas.2 

For  power  purposes  water  is  usually  measured  in  cubic  feet  of  flow  per  second. 
The  unit  weight  of  water  at  ordinary  temperature  is  62.5  pounds  per  cubic  foot. 
The  present  theory  of  the  flow  of  water  is  based  on  a  few  formulas.  The  funda- 
mental laws  of  falling  bodies  apply  also  to  the  flow  of  water.  Of  course  the  formu- 

1  Forestry  Hearing,  Am.  Inst.  E.  E.,  May,  1908. 

2  Merriman,  Treatise  on  Hydraulics. 


6  HYDROELECTRIC    DEVELOPMENTS    AND   ENGINEERING. 

las  derived  from  the  laws  of  gravity  cannot  be  directly  applied  to  hydraulics;  they 
must  be  changed  to  suit  conditions.     However,  by  the  judicious  use  of  the  funda- 
mental principles  and  common  sense  all  power  problems  may  be  easily  solved. 
The  principal  formulas  in  hydraulic  calculations  are: 


v  =  \/2  gh  =  8.03  V/z. 


q  =  av  =  a  ^2  gh  =  8.03  X  fl  V/z.  , 

v  —  velocity  of  flow  in  feet  per  second. 

q  —  quantity  of  flow  in  cubic  feet  per  second. 

h  =  head  or  height  through  which  the  water  falls. 

a  =  area  of  cross  section  of  falling  body  of  water. 

Whenever  the  formula  for  q  is  applied  to  water  issuing  from  an  orifice,  a  coeffi- 
cient must  be  introduced. 

Thus,  for  water  issuing  from  a  circular  orifice  the  quantity  coming  out  is  not 
q  —  \  TT  d?  V '2  gh,  but  q  =  c/4  it  d2  \/2  gh,  where  c  is  the  coefficient,  whose  value 
depends  on  the  sharpness  of  the  edges  of  the  opening.  This  is  true  for  the  flow  of 
water  issuing  from  a  square,  rectangular,  or,  in  fact,  any  shaped  orifice.  The  values 
of  the  coefficients  in  any  case  never  equal  unity. 

A  special  case  of  a  rectangular  orifice  is  what  is  known  as  the  'weir.'  The  weir 
in  general  is  an  opening  or  rather  a  notch  through  which  the  water  flows. 

The  fundamental  formula  used  with  weirs  is 

Q  -  i  <STg  bH*- 

Q  =  quantity  of  water  in  cubic  feet  per  second. 

b  =  width  of  opening  or  notch. 

H  =  height  of  the  water  surface  above  the  lowest  part  of  notch. 
H  is  measured  some  distance  back  of  the  weir. 

The  above  formula  undergoes  many  modifications  when  used  in  practice.  Many 
coefficients  must  be  used  in  connection  with  it.  Thus,  the  shape  of  the  notch,  whether 
rectangular,  square,  or  triangular,  the  sharpness  of  the  edges,  the  velocity  of  approach, 
the  form  of  curve  the  water  takes  in  flowing  over  the  weir,—  each  factor  introduces  a 
different  coefficient. 

When  water  is  carried  to  the  power  house  by  means  of  open  trenches  or  canals, 
or  through  long  pipe  lines,  some  energy  is  lost  by  friction  and  change  in  direction 

v2 
of  flow.     The  formula  for  loss  of  energy,  usually  termed  "loss  of  head,"  is  h  = 

2g 

This  formula  shows  that  the  loss  of  head  varies  with  the  square  of  the  velocity.  A 
very  important  factor  which  enters  into  hydraulic  computation  is  what  is  known  as 
the  hydraulic  radius.  It  is  not  a  radius  in  the  strict  sense;  it  is  a  ratio  and  is 
expressed  as  follows: — Area  of  cross  section  of  stream,  canal,  or  pipe,  in  square 
feet,  divided  by  the  length  of  the  wetted  perimeter  in  lineal  feet.  This  factor  is  of 


PROPOSITION.  7 

great  importance  when  calculating  the  flow  of  water  through  canals,  ditches,  and 
pipes. 

The  slope  of  a  stream,  canal,  or  pipe  line  is  its  fall  in  feet  per  mile,  or  is  the  drop 
in  any  measured  length. 

For  the  velocity  of  flow  in  rivers  having  a  uniform  cross-sectional  area,  with  a 
given  slope,1 

velocity  in  feet  per  second  =  Vhydraulic  radius  X  slope  in  feet  per  mile. 
For  canals  and  ditches  of  uniform  area  and  smooth  bottom, 


velocity  in  feet  per  second  =  x/hydraulic  radius  X  2   X  slope  in  feet  per  mile. 

By  inversion  is  obtained  the  formula  for  the  hydraulic  gradient  or  slope  for  a 
given  velocity  in  feet  per  mile. 

(velocity  in  feet  per  second)2 


thus  = 


Hydraulic  Radius  X  2 


A  change  in  cross  section  will  alter  the  value  of  the  hydraulic  gradient,  that  is, 
making  the  ditch  or  canal  wider  or  narrower,  or  changing  the  form.  Too  swift  a 
velocity  must  not  be  chosen,  because  the  water  will  scour  the  sides  of  the  canal.  Of 
course  when  the  canal  is  made  of  concrete  this  factor  is  of  little  account;  the  friction 
loss  is  of  greater  importance  than  the  scouring  effect  of  water  on  concrete. 

Gross  Horsepower.   The  gross  horsepower  of  a  mass  of  falling  water  is 

Q  X  H  X  62.3 

—  -•  or  0.00189  QH. 
33,000 

Q    =  cubic  feet  of  water  discharge  per  minute. 

H  —  head  in  feet. 

62.3,  weight  per  cubic  foot  of  water  (at  60°  F.). 

As  water  is  usually  measured  in  cubic  feet  per  second,  the  above  formula  is  pref- 
erably  taken  as  g 

-  or  0.1134  QH. 
550 

To  compute  the  gross  horsepower  of  a  running  stream  the  same  formula  may  be 
used. 

H  in  this  case  represents  the  theoretical  head  due  to  the  velocity  of  the  water 

in  the  stream, 


2  g        64.4 

v  =  velocity  of  water  in  feet  per  second. 
Q  =  cubic  feet  of  water  per  second. 
The  gross  horsepower  =  0.1134  QH. 

Water  wheels  or  turbines  do  not  utilize  the  gross  head,  as  friction  in  the  head- 
race and  in  the  turbine  itself  has  to  be  considered. 

1  Hiscox,  Hydraulic  Engineering,  page  57. 


8  HYDROELECTRIC    DEVELOPMENTS    AND    ENGINEERING. 

Miner's  Inch.  During  the  early  days  of  hydraulic  engineering  in  America  the 
Miner's  Inch  originated  in  California,  and  is  a  method  of  measurement  adopted 
by  the  various  ditch  companies  in  disposing  of  water  for  irrigation  and  mining. 
The  miner's  inch  is  equal  to  the  flow  of  water  through  an  orifice  one  inch  square, 
in  a  1.25  inch  plank,  and  the  surface  of  the  water  being  6  inches  above  the  top  edge 
of  the  opening.  This  method  of  measuring  is  becoming  obsolete  and  is  being 
replaced  by  the  more  accurate  system  of  weir  measurements. 

Weir  Dam.  Select  a  stretch  on  the  stream  or  ditch  which  will  afford  as  straight 
and  uniform  a  course  as  possible.  If  the  water  is  carried  in  a  flume  through  any 
part  of  its  course,  make  all  measurements  in  the  flume.  Lay  off  a  distance  of  say 
300  feet;  measure  the  width  of  the  stream  at  the  surface  of  the  water  at  about  six 
different  places  in  this  distance,  and  obtain  the  average  width;  likewise  at  these 
same  points  measure  the  depth  of  water  at  three  or  four  places  across  the  stream, 
and  obtain  the  average  depth.  Next  drop  a  float  in  the  water,  noting  the  number 
of  seconds  it  takes  to  travel  the  given  distance.  From  this  can  be  calculated  the 
velocity  of  the  water  in  feet  per  second.  The  cubic  quantity  is  the  product  obtained 
by  multiplying  the  average  width  in  feet  by  the  average  depth  in  feet  by  the  velocity, 
which  (if  in  feet  per  second)  will  give  the  flow  of  the  stream  in  cubic  feet  per  second. 
From  the  figures  so  obtained  20  per  cent  must  be  deducted,  as  the  surface  velocity 
of  the  water  is  greater  than  the  average  velocity. 


FIG.  i. — Weir  Dam. 

When  the  stream  is  of  sufficient  depth  —  say  three  feet  or  over  —  the  average 
velocity  can  be  more  easily  obtained  by  using  a  pole  to  one  end  of  which  is  attached 
a  stone  or  piece  of  lead  of  necessary  weight  to  allow  the  pole  to  sink  nearly  to  the 


PROPOSITION. 


UNIV.0F  CA1 


bottom.     In  this  way  the  velocities  at  the  surface  and  bottom  of  the  stream  counter- 
act one  another  and  a  closer  approximation  to  the  average  velocity  is  obtained. 

Place  a  board,  a,  across  the  stream  at  some  point  which  will  allow  a  pond  to  form 
above  (see  Fig.  i).  The  board  should  have  a  notch,  b,  with  both  edges  sharply 
beveled  towards  the  intake  as  shown.  The  bottom  of  the  notch,  called  the  "crest" 
of  the  weir,  should  be  perfectly  level  and  the  sides  vertical.  In  the  pond  back  of 
the  weir,  at  a  distance,  d,  not  less  than  the  length  of  the  weir,  drive  a  stake,  e,  near 
the  bank,  with  its  top  precisely  level  with  the  crest.  Measure  the  depth,  c,  of  water 
over  the  top  of  stake,  and  then  from  Table  I  calculate  the  amount  of  water  flowing 
over  the  weir. 

TABLE  I.  —  SHOWING  QUANTITY  OF  WATER  PASSING   OVER  WEIRS  IN  CUBIC  FEET 

PER  MINUTE. 


$  £ 

rt  J3 

Cubic  feet 

S  8 

ot  si 

Cubic  feet 

&  8 

t»  .e 

Cubic  feet 

+->      O 

ed  .c 

Cubic  feet 

£    S 
«   J2 

Cubic  feet 

*  .S 

per  minute 

*  1 

per  minute 

*J 

per  minute 

*| 

per  minute 

*| 

per  minute 

*o    - 

passed  for 

"o 

passed  for 

"o 

passed  for 

^ 

passed  for 

"o    - 

passed  for 

J2   °53 

each  foot  of 

I- 
j-  '53 

each  foot  of 

x  '53 

each  foot  of 

t. 

ja  '53 

each  foot  of 

u 

j-  "53 

each  foot  of\ 

fc  * 

length  of 

S* 

length  of 

£* 

length  of 

S^ 

length  of 

Z* 

length  of 

Qg 

weir. 

0      r 

Q   o 

weir. 

Q  § 

weir. 

<U     ri 

Q  o 

weir 

Q  g 

weir. 

i 

4-85 

4 

38.80 

7 

89.82 

10 

153-35 

14 

254   03 

«1 

5-78 

4& 

40.63 

7* 

92.  16 

tol 

156.20 

I4l 

260.83 

li 

6.68 

4f 

42.49 

71 

94.67 

IO| 

I59-I4 

143 

267.77 

if 

7.80 

4f 

44-39 

7l 

97.11 

lof 

162.07 

i4i 

274.70 

rj 

8.90 

4* 

46.29 

7§ 

99-5° 

IO^ 

164.99 

15 

281.72 

if 

10.  OO 

4J 

48.22 

7l 

IO2.  IO 

io| 

167.89 

I5| 

288.82 

4 

11.23 

4| 

50.20 

7! 

104.63 

IO} 

169.92 

15} 

295-93 

if 

12.45 

41 

52.18 

7s 

107.13 

I0j 

I73.90 

iSf 

303-IO 

2 

I3-72 

5 

54.22 

8 

109.74 

II 

176.92 

16 

310.36 

2k 

15.02 

Si 

56.25 

8£ 

112.31 

III 

179-94 

i6J 

3I7-69 

aj 

16.36 

Si 

58-33 

81 

114.91 

"1 

182.99 

16} 

325-03 

a| 

17-75 

5| 

60.42 

8| 

1  1  7  •  5  r 

III 

186.03 

i.6| 

332.42 

aft 

19.17 

si 

62.55 

8J 

120.  r8 

"I 

189.13 

17 

339-91 

af 

20.63 

si 

64.68 

81 

122.82 

Ilf 

192.  20 

«7i 

347-45 

*i 

22.  II 

5? 

66.86 

8} 

125.52 

III 

I95-32 

17! 

355-02 

af 

23-63 

5^ 

68.98 

8g 

128.  14 

"1 

198.47 

i7i 

362.77 

3 

25.20 

6 

71.27 

9 

130-93 

12 

201.59 

18 

370  34 

3i 

26.78 

6£ 

73  -  45 

9^ 

133  65 

Mi 

207.94 

18! 

378.12 

3i 

28.43 

6i 

75-77 

9i 

136.43 

iaj 

2I4.32 

i8| 

385-87 

3f 

30.06 

61 

78.04 

9f 

139.18 

12! 

22O.  76 

i8| 

393-66 

3i 

31-75 

6i 

80.36 

9i 

141.99 

13 

227.30 

19 

401.63 

3& 

33-45 

61 

82.63 

9§ 

144.80 

y| 

233.93 

i9i 

409  .  58 

3? 

35-22 

6f 

85.04 

9^ 

147.64 

13} 

240.54 

iQi 

417.48 

35 

36.98 

61 

87-43 

9! 

i50-47 

13! 

247.22 

19! 

425.68 

There  are  certain  proportions  which  must  be  observed  in  the  dimensions  of  this 
notch.  Its  length  should  be  between  four  and  eight  times  the  depth  of  water  over 
the  crest  of  the  weir,  and  not  over  two-thirds  the  width  of  water  on  the  upstream 
side;  also  the  pond  above  the  weir  should  be  sufficiently  large  to  reduce  the  velocity 
of  flow  or  "approach  "  to  less  than  2  feet  per  second.  In  order  to  obtain  these 
results  it  will  probably  be  necessary  to  experiment  to  some  extent.  An  example 
may  serve  to  better  explain  this  procedure. 

First,  roughly  gauge  the  stream  to  be  measured,  by  the  cross-section  and  velo- 
city method.  Suppose  the  width  is  found  to  be  4.5  feet,  the  depth  1.5  feet,  and  the 


10  HYDROELECTRIC    DEVELOPMENTS    AND    ENGINEERING. 

average  velocity  3  feet  per  second.  The  stream  is  then  carrying  approximately 
1215  cubic  feet  per  minute. 

Next  it  is  necessary  to  ascertain  the  size  of  weir  to  discharge  approximately  this 
amount  of  water.  The  length  of  notch  must  be  from  four  to  eight  times  the  depth. 
Assuming  an  average  of  say  six  times  the  depth,  which  will  be  within  the  limits, 
from  Table  I  it  will  be  found  by  trial  that  a  weir  72  inches  long,  with  a  depth  of 
12  inches,  will  discharge  1196  cubic  feet  of  water  per  minute.  This,  therefore,  is 
approximately  the  size  of  weir  required. 

Take  a  board  of  sufficient  length  to  reach  well  across  the  stream  and  cut  the 
notch  72  inches  long  and  about  16  inches  deep,  as  it  should  be  somewhat  deeper 
than  the  water  flowing  over  it.  The  vertical  height  from  the  crest  to  water  line  on 
downstream  side  should  be  at  least  twice  the  depth  of  water  on  the  crest,  or  approx- 
imately 26  inches  in  this  case.  If  the  length  of  the  notch  is  greater  than  two-thirds 
the  width  of  the  water  above  the  dam,  it  is  necessary  to  either  construct  a  higher 
weir,  in  order  to  raise  the  water  level,  or  to  cut  away  the  sides  of  the  bank,  as  the 
ratio  must  not  be  exceeded. 

It  is  of  course  essential  that  there  be  no  leaks  around  or  under  the  weir.  All 
the  water  must  pass  through  the  notch.  Canvas  or  sacking  laid  under  the  water 
against  the  dam  will  be  found  effective  in  this  connection.  With  the  weir  so  con- 
structed, measure  the  depth  of  the  water  over  the  stake,  and  by  the  use  of  the  table 
ascertain  the  actual  quantity  flowing  over  the  weir. 

Table  I  will  give  results  sufficiently  close  for  all  practical  purposes  and  is  read 
as  follows: 

Suppose  the  head  on  the  crest  is  nf  inches  and  the  weir  is  6  feet  wide.  In  the 
table  opposite  nf  will  be  found  192.2,  which  is  the  cubic  feet  discharge  for  a  weir 
i  foot  wide;  this  multiplied  by  6  gives  the  discharge  for  the  above  example  (1153.2 
cubic  feet). 

If  a  more  accurate  measurement  is  desired  the  following  formula  should  be  used: 

Q  =  3-33  (I*  ~  -2  H]  Hi 

L  =  length  of  weir  in  feet. 
H  =  head,  in  feet,  on  crest. 
Q  =  cubic  feet  of  water  per  second. 

Flow  of  River.  In  order  to  calculate  the  amount  of  water  flowing  in  a  large  stream 
or  river  in  all  seasons  observation  stations  have  to  be  established.  These  stations 
are  nothing  more  than  a  gauge-rod  so  set  that  the  height  of  the  water  can  be  easily 
read.  In  order  to  assure  a  true  record  of  the  volume  of  water  flowing  it  is  essential 
to  establish  such  stations  on  the  main  stream  and  tributaries.  The  levels  must  be 
read  every  day  for  a  number  of  years,  and  during  the  flood  season  they  must  be  read 
two  or  three  times  during  the  day  and  the  average  taken.  From  the  observations 
of  the  depth  of  water  the  area  of  the  cross  section  of  each  portion  of  the  stream 
considered  as  a  number  of  superimposed  horizontal  layers  is  computed;  the  cross- 
section  area  of  each  assumed  layer  multiplied  by  the  mean  velocity  of  that  layer  gives 


PROPOSITION. 


II 


a  partial  discharge.     The  sum  of  the  partial  discharges  is  the  total  discharge  of  the 
stream. 

At  the  several  stations  the  flow  of  the  river  is  measured  and  recorded  by  current 
meters,  of  which  there  are  several  on  the  market;  Fig.  2  illustrates  a  type  of  same. 
On  the  bottom  of  the  rod  is  a  lead  weight  to  keep  the  instrument  in  an  upright  position. 
The  water  flows  against  the  buckets,  and  the  number  of  revolutions  is  recorded 
by  an  electrical  indicator. 


FIG.  2. — Current  Meter. 

A  more  primitive  way  to  measure  the  velocity  of  a  stream  is  given  under  Weir 
Dams;  a  more  scientific  way  is  by  means  of  the  Venturi  meter.  This  meter  was 
invented  by  Herschel  in  1887, *  and  consists  of  a  contracted  pipe,  with  two  gauges, 
one  at  the  contraction  and  the  other  in  the  full  size.  When  there  is  no  motion  of 
water  in  the  pipe  both  gauges  read  alike;  when  the  flow  becomes  sufficiently  rapid, 
the  gauge  at  the  throat  will  indicate  vacuum,  while  the  other  will  continue  to  indi- 
cate the  pressure  due  to  head.  From  the  difference  in  the  two  readings,  and  the 
constant  of  the  meter,  the  velocity  of  the  water  through  the  throat  can  be  computed. 
By  applying  a  self-recording  differential  gauge  the  velocity  and  quantity  of  water  may 
be  registered. 

Measurements  of  flow  as  outlined  above  are  made  to  cover  a  considerable  range 
of  gauge  height.  They  are  then  plotted  on  coordinate  paper,  with  gauge  heights  for 
ordinates  and  discharges  as  abscissas,  and  a  smooth  curve,  called  the  rating  curve,  is 
drawn  through  the  points.  From  this  curve  a  rating  table  is  made  which  shows  the 
discharge  of  the  stream  for  any  gauge  height. 

The  data  necessary  for  the  construction  of  a  rating  table  for  a  gauging  station 
are  the  results  of  the  discharge  measurements,  which  include  the  record  of  stage 

1  Trans.  Am.  Soc.  C.  E.,  vol.  17,  page  228. 


12 


HYDROELECTRIC    DEVELOPMENTS    AND    ENGINEERING. 


of  the  river  at  the  time  of  measurement,  the  area  of  the  cross  section,  the  mean  velo- 
city of  the  current,  and  the  quantity  of  water  flowing,  and  a  thorough  knowledge 
of  the  conditions  at  and  in  the  vicinity  of  the  station.  The  construction  of  the  rat- 
ing table  depends  on  the  following  laws  of  flow  for  open  permanent  channels:  (i)  the 
discharge  will  remain  constant  so  long  as  the  conditions  at  and  near  the  gauging 
station  remain  constant;  (2)  the  change  of  slope  due  to  the  rise  and  fall  of  the  stream 
being  neglected,  the  discharge  will  be  the  same  whenever  the  stream  is  at  a  given 
stage;  (3)  the  discharge  is  a  function  of,  and  increases  gradually  with,  the  stage. 

The  plotting  of  results  of  the  various  discharge  measurements,  using  gauge  heights 
as  ordinates  and  discharge,  mean  velocity,  and  area  as  abscissas,  will  define  curves 
which  show  the  discharge,  mean  velocity,  and  area  corresponding  to  any  gauge  height. 
For  the  development  of  these  curves  there  should  be  a  sufficient  number  of  discharge 
measurements  to  cover  every  known  variation  in  the  height  of  the  stream.  Fig.  3 


] 

/ 

-' 

oca 

X" 

X* 

/ 

X 

t 

/ 

X 

! 

...    ,' 

t 

:>•'-" 

^j 

^ 

j 

,r 

,-' 

X 

I 

L 

MEASUREMENTS    1 

Ki   l°Of  NO.  1 
•     I9O3  NO  f  T 
1904  NO  8 
I90S  NO  9  n 
1906    NO  14 

9? 

g! 

^- 

t 

1 

y 

>a 

it 

& 

X 

1 

i 

/ 

? 

&% 

I 

L 

t 

% 

/: 

\ 

-'-S 

/ 

/ 

S 

7 

v7 
g 

//' 

£ 

7 

*/ 

7 

? 

/ 

/ 

7 

^ 

7s 

/ 

r 

/? 

[/ 

! 

/8 

"<. 

/ 

/ 

"•/ 

/• 

&> 

I? 

£ 

,*A 

i 

j>i 

I- 

l/e 

0 

lOClt 

z 

y  in 

a 

feec 

it. 

per 

0 

.seed 
•j 

na 

0 

tt 

so 

Jrc 

eo 

^ 

^L, 
Ijj 

ai-Q 

00 

feat 

I6< 

«8 

ao 

iao 

0                10,000          20.000          30.000          4O.OOO           50.000          60.000          70.000           60.00O          90,000"        100.000           "0.000          120,000          130.000           l<K>.000           IK 
Discharge  in  second-feet 

FIG.  3. — Method  of  Plotting  Curves  for  Discharge,  Mean  Velocity  and  Area  of  Rivers. 

shows  a  typical  rating  curve  with  its  corresponding  mean  velocity  and  area  curves.1 
As  the  discharge  is  the  product  of  two  factors,  the  area  and  the  mean  velocity,  any 
change  in  either  factor  alone  will  produce  a  corresponding  change  in  the  discharge. 
The  curves  are  therefore  constructed  in  order  to  study  each  independently  of  the 
other. 

The  area  curve  can  be  definitely  determined  from  accurate  soundings  extending 
to  the  limits  of  high  water.  It  is  always  concave  toward  the  horizontal  axis  or  on 
a  straight  line  unless  the  banks  of  the  stream  are  overhanging. 

p 
1  Water-Supply  and  Irrigation  Paper  No.  192  of  the  U.  S.  Geological  Survey. 


PROPOSITION.  13 

The  form  of  the  mean  velocity  curve  depends  chiefly  on  the  surface  slope,  the 
roughness  of  the  bed,  and  the  cross  section  of  the  stream.  Of  these  the  slope  is 
the  principal  factor.  In  accordance  with  the  relative  change  of  these  factors  the 
curve  may  be  either  a  straight  line,  a  curve,  convex  or  concave,  or  a  combination  of 
the  three. 

From  study  of  the  conditions  at  any  gauging  station  the  form  which  the  vertical 
velocity  curve  will  take  can  be  predicted,  and  it  may  be  extended  with  reasonable 
certainty  to  stages  beyond  the  limits  of  actual  measurements.  It  is  used  principally 
in  connection  with  the  area  curve  in  locating  errors  in  discharge  measurements  and 
in  constructing  the  rating  table. 

The  discharge  curve  is  drawn  from  the  measurements  of  the  discharge.  The 
curve  may  have  certain  of  its  points  located  between  and  beyond  those  given  by 
the  actual  measurements  by  means  of  the  curves  of  area  and  mean  velocity.  Under 
normal  conditions  the  discharge  curve  is  concave  toward  the  horizontal  axis  and 
is  generally  parabolic  in  form. 

The  chart  is  readily  understood;  the  term  "  second-feet"  is  an  abbreviation  for 
cubic  feet  per  second,  and  is  the  rate  of  discharge  of  water  flowing  in  a  stream 
i  foot  wide,  i  foot  deep  at  the  rate  of  i  foot  per  second. 

Profile  of  River.  To  ascertain  the  slope  or  fall  of  a  river,  elevations  of  the  river 
level  have  to  be  read  and  plotted,  so  that  the  best  locations  for  dams  can  be  seen, 
see  Fig.  4.  The  abscissas  give  the  distance  in  miles  and  the  ordinates  give  the 
elevations  in  feet;  the  latter  are  preferably  read  as  elevations  above  the  sea  level. 


i,r»oo 


1,250 ~ 


1,000  = 

i 


0. Miles  5 


FIG.  4. — Method  of  Plotting  River  Bed.     (Alcoy  River.) 

Government  Reports.  The  governments  of  nearly  all  countries  maintain  depart- 
ments for  studying  the  flow  of  streams,  and  official  reports  on  stream  measurement 
are  regularly  issued.  The  United  States  Geological  Survey  has  for  more  than 
twenty  years  been  studying  the  various  phases  of  the  water  resources  of  the  United 
States.  The  results  of  most  of  these  studies  have  been  published  as  Water-Supply 
Papers.  Some,  however,  appear  in  annual  reports  and  bulletins.  These  studies 


14  HYDROELECTRIC    DEVELOPMENTS    AND    ENGINEERING. 

include  measurements  of  the  flow  of  streams,  determination  of  river  profiles,  and 
collection  of  data  in  regard  to  water-power  development. 

These  data  give  the  records  for  a  number  of  years  of  the  rainfall,  flow  of  streams 
in  cubic  feet  per  second  for  wet  and  dry  seasons,  and  in  some  cases  give  the  gross 
horsepower  which  could  probably  be  developed,  and  occasionally  offer  suggestions 
to  the  hydraulic  engineer.  An  excellent  example  is  taken  from  the  introduction  of 
"The  Relation  of  the  Southern  Appalachian  Mountains  to  the  Development  of 
Water  Power."  l 

According  to  estimates  made  by  the  United  States  Geological  Survey  there  is  a 
minimum  of  about  2,800,000  indicated  horsepower  developed  by  the  rivers  having 
their  head  waters  in  the  Southern  Appalachian  Mountains.  Mature  consideration 
of  the  condition  leads  the  Survey  to  estimate  that  at  least  50  per  cent  and  probably 
much  more  of  this  indicated  power  is  available  for  economic  development.  If  auxil- 
iary power  were  provided,  it  would  be  profitable  to  develop  up  to  2.5  times  this 
amount. 

Full  development  of  storage  facilities  would  increase  the  minimum  from  2  to 
30  times.  Obviously  an  estimate  of  present  value  based  on  50  per  cent  of  the  mini- 
mum indicated  horsepower  is  sure  to  be  extremely  conservative.  The  rental  of 
1,400,000  horsepower  at  $20  per  horsepower  per  year  would  amount  to  an  annual 
return  of  $28,000,000.  This  amount  is  equal  to  a  gross  income  of  3  per  cent  on  a 
capital  of  about  $933,000,000.  Some  of  this  power  has  already  been  developed, 
but  a  very  small  proportion  —  hardly  enough  to  make  any  appreciable  showing 
when  the  enormous  resources  of  the  region  are  taken  into  account. 

It  has  been  estimated  that  in  the  United  States  more  than  30,000,000  horse- 
power are  available,  and  under  certain  assumptions  as  to  storage  reservoirs  this 
amount  can  be  increased  to  150,000,000  horsepower  or  possibly  more.  In  an  address 
at  the  conference  on  the  "Conservation  of  the  Natural  Resources,"  at  Washington, 
D.C.,  May,  1908,  St.  Clair  Putnam  made  the  following  statement  on  the  value 
of  the  water  powers  in  the  United  States: 

"Using  the  smaller  figure  of  30  million  horsepower  as  an  illustration;  to  develop 
an  equal  amount  of  energy  in  our  most  modern  steam  electric  power  plants  would 
require  the  burning  of  nearly  225,000,000  tons  of  coal  per  annum,  and  in  the  average 
steam  engine  plant,  as  now  existing,  more  than  6,000,000  tons  of  coal,  or  50  per  cent 
in  excess  of  the  total  coal  production  of  the  country  in  1906.  At  the  average  price 
of  $3.00  per  ton,  it  would  require  the  consumption  of  coal  costing  $1,800,000,000 
to  produce  an  equivalent  power  in  steam  plants  of  the  present  general  type." 

Of  this  immense  water  power  available,  only  a  small  percentage  is  developed, 
estimated  to  be  about  3,000,000  horsepower. 

Nearly  every  state  in  the  Union  has  large  water  powers  available.  It  has  been 
estimated  that  the  upper  Mississippi  and  its  tributaries  have  an  available  water 
power  of  about  2,000,000  horsepower;  that. of  the  Southern  Appalachian  region,  about 
3,000,000;  and  that  of  the  State  of  Washington  alone,  about  3,000,000  horsepower. 

1     Forest  Service,  Circular  144,  U.  S.  Department  of  Agriculture. 


PROPOSITION.  1 5 

ECONOMY   IN   DEVELOPMENT. 

Preliminaries.  The  first  cost,  efficiency,  and  economy  of  an  hydraulic  develop- 
ment depend  primarily  on  the  ability  of  the  designer.  This  fact,  although  of  great 
importance,  is  often  overlooked  by  the  investors. 

When  a  plant  is  to  be  built  for  a  railroad  company  or  other  large  corporation, 
the  designer  is  frequently  in  the  employ  of  the  company;  sometimes  contracts  are 
let  to  firms  of  contracting  engineers,  who  may  furnish  the  plans  only  or  both  the 
plans  and  the  entire  plant. 

Contracts  may  be  made  between  investors  and  engineers  for  professional  services 
for  specific  amounts,  or  for  a  percentage  plus  disbursement,  or  for  fixed  sum  plus 
disbursements.  Capitalists  or  corporations,  before  letting  contracts,  should  make 
thorough  investigations,  not  only  of  the  financial  and  business  reputation  of  con- 
sulting and  contracting  engineers,  but  should  convince  themselves  of  the  ability  of 
the  firms  and  their  staffs,  particularly  of  the  designer  in  charge.  Frequently  during 
the  course  of  construction  or  after  the  completion  of  a  plant,  an  experienced  designer 
shows  where  thousands  of  dollars  could  have  been  saved  by  engaging  engineers 
who  are  specialists  in  the  design  of  plants. 

Reports  made  on  plants  after  their  construction  have  shown  in  some  instances 
that  in  stations  of  10,000  K.W.  capacity  several  hundred  thousand  dollars  could 
easily  have  been  saved;  while  on  plants  of  50,000  K.W.  capacity  reports  have  been 
made  showing  where  over  a  million  dollars  could  have  been  saved. 

Problems  Involved.  The  problems  involved  in  the  design  of  hydroelectric  plants 
are  those  of  first  cost  of  construction,  equipment,  operation,  and  maintenance. 

It  is  the  ultimate  aim  to  produce  electricity  at  a  minimum  of  expense.  To  accom- 
plish this  end,  experience  is  necessary.  It  is  not  the  province  of  the  engineer  as  a 
designer  of  hydroelectric  plants  to  design  any  particular  machine,  such  as  turbines, 
generator,  oil-switches,  etc.,  but  to  provide  a  selection  of  different  makes,  each 
designed  to  perform  its  function  in  the  most  economical  manner;  and  to  have  these 
machines  properly  combined  to  form  one  complete  unit  for  the  purpose  of  gener- 
ating electricity  from  water  on  a  satisfactory  commercial  basis.  Since  on  the  original 
design  depends  the  economical  operation  of  the  plant,  great  care  and  foresight  must 
be  exercised  in  the  selection  and  arrangement  of  the  devices;  for  instance,  a  turbine 
for  low  head  would  not  be  so  efficient  if  connected  to  a  high  head,  and  vice  versa. 
The  location  of  the  power  plant  building  must  be  chosen  so  as  to  obtain  the  greatest 
head  with  the  least  expenditure  for  head  or  tail  race.  As  a  general  rule,  the  higher 
the  head  the  cheaper  will  be  the  installation. 

In  designing  a  plant,  and  in  the  selection  and  arrangement  of  the  equipment, 
some  originality  should  be  exercised.  No  designer  should  unreservedly  copy  the 
scheme  of  an  existing  plant,  since  what  might  be  economical  in  one  would  possibly 
be  the  reverse  in  the  other.  Any  attempt  to  standardize  the  design  of  hydraulic 
plants  is  practically  impossible.  However,  in  the  design  of  a  single  station,  a 
system  of  standardization  must  be  adopted  to  minimize  expenses  in  design,  construc- 
tion, and  operation.  i . 


1 6  HYDROELECTRIC    DEVELOPMENTS    AND   ENGINEERING. 

The  work  embodied  in  a  complete  installation  comprises  hydraulic,  mechanical, 
structural,  and  electrical  work.  They  are  necessarily  closely  allied,  and  it  is  essential 
that  the  design  of  the  entire  undertaking  be  placed  under  one  engineer.  If  this 
method  is  not  followed,  confusion  may  possibly  result,  delaying  the  work  and  incur- 
ring additional  expense.  If  the  work  is  divided  among  several  designers,  complete 
cooperation  may  not  exist,  and  the  various  designers  will  probably  conflict  with 
one  another;  for  instance,  the  same  article  or  work  may  appear  in  two  or  more 
drawings  or  specifications,  or  may  be  entirely  omitted,  one  designer  considering  it  a 
part  of  another's  work. 

Designing  Staff.  Having  secured  the  necessary  data,  and  fixed  the  size  of  the 
plant,  the  design  must  be  carried  on  systematically.  As  the  scope  of  power  plant 
design  is  a  broad  one,  it  is  necessary  in  large  plants  to  employ  assistants,  designers, 
and  draughtsmen. 

For  instance,  in  designing  a  50,000  K.W.  plant  the  designer's  staff  may  consist 
of  one  assistant,  who  is  familiar  with  the  various  branches  required  in  the  complete 
plant;  four  or  five  draughtsmen  (assistant  designers),  who  are  experienced  in  the 
various  branches  previously  mentioned.  The  hydraulic  or  mechanical  designer 
should  arrange  the  general  scheme,  such  as  arrangement  of  turbines  and  particularly 
the  headrace  and  the  foundation  of  the  building;  the  electrical  designer,  the  elec- 
trical layout,  such  as  wiring  and  switchboard,  etc.,  and  will  work  in  conjunction 
with  the  mechanical  engineer  to  establish  the  size  of  the  building.  The  structural 
design  depends  upon  the  data  supplied  by  the  mechanical  and  electrical  engineers 
for  the  skeleton  of  the  building,  floor  loads,  roof  trusses,  etc.  The  structural  engineer 
is  often  called  upon  to  assist  in  the  design  of  the  gates  and  penstocks,  also  to  design 
the  high  tension  transmission  towers. 

Architects  are  seldom  employed,  as  is  evidenced  from  the  severely  plain  power 
houses,  of  which  there  are  numerous  examples.  However,  in  the  last  few  years 
occasional  plants  have  been  erected  indicating  that  architectural  talent  has  been 
employed. 

In  order  to  bring  about  system  and  economy  in  the  draughting  department,  a  few 
tracers  may  be  employed  to  do  less  important  work,  such  as  tracing  and  lettering. 
By  shifting  the  tracers  around,  as  necessity  requires,  they  receive  proper  training 
and  a  general  knowledge  of  the  whole  power  plant  construction.  While  the  check- 
ing of  all  drawings  is  necessary,  it  is  not  feasible  to  employ  a  checker  to  verify  draw- 
ings of  all  branches.  While  he  may  check  the  dimensions  in  conjunction  with  the 
designer  of  the  individual  features,  it  is  impossible  to  find  a  checker  to  verify  the 
design  as  is  usually  done  in  structural  steel  branches.  Such  checkers  have  to  be 
familiar  not  only  with  the  general  scheme  but  with  the  detail  of  every  feature 
employed  in  the  design  of  the  complete  plant.  Therefore  the  designers  of  the  differ- 
ent branches  should  check  each  other's  drawings. 

Drawings  and  Specifications.  For  convenience  of  the  draughting  department 
and  especially  the  field,  all  drawings  should  be  standardized.  Drawings  larger 
than  24  X  36  inches  are  cumbersome  and  inconvenient  for  constructors.  Multi- 
plicity of  drawings  should  be  avoided.  Drawings  of  the  several  branches  must  not 


PROPOSITION.  17 

appear  on  one  sheet,  i.e.,  the  structural  steel  must  not  be  on  the  same  sheet  as  the 
foundation  work  or  part  of  same.  It  is  common  practice  to  begin  the  work  after  a 
few  drawings  which  later  undergo  revision  as  construction  proceeds.  Unless 
a  system  of  revision  numbers  is  used,  subsequent  construction  is  seriously 
handicapped. 

Duplicate  sets  of  blue  prints  should  be  required  from  the  manufacturers,  one  set 
for  the  office  files,  the  other  to  be  returned  with  indicated  changes  or  approval  as  the 
case  may  be.  All  drawings,  as  well  as  incoming  and  outgoing  blue  prints,  should 
be  properly  indexed  on  a  two-card  filing  or  other  efficient  system. 

Before  submitting  plans  and  specifications  to  contractors  for  bids,  they  should 
be  complete  in  every  respect,  in  fact  they  should  be  working  drawings.  The  speci- 
fications must  be  drawn  up  after  the  plans  are  finished  or  practically  finished,  and 
should  be  so  drawn  as  to  simplify  and  explain  the  plans. 

Each  contractor's  specifications  should  start  where  that  of  the  previous  con- 
tractor stopped,  so  that  the  work  will  not  overlap,  or  gaps  be  left.  It  is  not  infre- 
quent practice  by  plant  designers  to  consult  engineering  salesmen  or  manufacturers, 
from  whom  it  is  always  advisable  to  secure  specifications,  and  draw  comparisons 
between  the  products  of  the  various  manufacturers. 

As  stated,  specifications  and  plans  have  to  be  complete  before  they  are  sub- 
mitted for  bids,  in  order  to  minimize  in  extras. 

Extras  are  usually  overcharged,  since  it  is  to  these  that  some  contractors  look 
for  profit.  For  instance,  the  contract  for  structural  steel  may  be  let  from  prelimi- 
nary drawings,  on  a  per  pound  basis,  say  from  three  to  four  cents;  when,  however, 
the  plans  are  worked  out  in  detail,  it  will  be  found  that  there  are  a  number  of  stair- 
cases, ladders,  railings,  etc.,  not  shown  in  preliminary  drawings,  and  the  contractor, 
on  a  plea  that  more  workmanship  is  required  with  this  kind  of  work,  will  raise  his 
price  to  seven  or  eight  cents  per  pound  or  even  more.  For  certain  apparatus,  such 
as  turbines,  generators,  and  overhead  cranes,  etc.,  preliminary  bids  may  be  asked 
for  from  rough  drawings  to  ascertain  the  approximate  cost,  of  the  plant.  This  may 
be  necessary  when  the  design  is  limited  to  a  fixed  sum. 

Field  Office.  As  most  hydraulic  developments,  particularly  those  of  large  size, 
are  far  away  from  the  main  engineering  organization,  it  is  necessary  to  have  an 
experienced  and  capable  engineer  with  a  good  staff  in  the  field.  Cases  always  arise 
during  construction  where,  for  various  reasons,  the  drawings  cannot  be  strictly 
followed,  and  to  secure  the  necessary  instruction  from  the  home  office  consumes 
much  time  and  may  cause  confusion.  Most  of  the  errors  discovered  in  the  process 
of  construction  are  trivial  in  themselves,  but  affect  the  remainder  of  the  plant.  Any 
modifications  of  the  original  drawings  made  in  the  field  must  be  undertaken  only  by 
an  experienced  resident  engineer,  who  must  have  sufficient  authority  from  the  head 
office.  All  field  corrections,  however,  must  be  at  once  reported  to  the  main  office, 
so  that  corresponding  changes  can  be  made  on  the  original  design. 


1 8  HYDROELECTRIC    DEVELOPMENTS    AND   ENGINEERING 

BIBLIOGRAPHY. 

TREATISE  ON  HYDRAULICS.     1903.    Mansfield  Merriman. 

HYDRAULIC  AND  HYDRAULIC  MOTORS.     P.  J.  Weisbach.     Translated  by  A.  J.  Dubois. 

A  TREATISE  ON  HYDRAULICS.     1901.    Henry  T.  Bovey. 

HYDRAULICS.     1907.    L.  M.  Hoskins. 

RIVER  DISCHARGE.     1907.     J.  C.  Hoyt  and  N.  C.  Grover. 

NOTES  ON  HYDROELECTRIC  PLANT  ORGANIZATION  AND  OPERATION.    Farley  Osgood.    Pro.  Am.  Inst. 

E.  E.,  April,  1907. 

CONSERVATION  OF  POWER  RESOURCES.     H.  St.  Clair  Putnam.    Pro.  Am.  Inst.  E.  E.,  August,  1908. 
WATER  POWER  DEVELOPMENT  IN  THE  NATIONAL  FORESTS.     F.  G.  Baum.    Pro.  Am.  Inst.  E.  E., 

July,  1908. 
SOME  PRELIMINARY  STEPS  IN  HYDROELECTRIC  ENGINEERING.    Frank  Koester.    Electrical  Review 

and  Western  Electrician,  Nov.  28,  1908. 

RAINFALL  OF  THE  UNITED  STATES.  A.  J.  Henry.  Bulletin  D,  U.  S.  Weather  Bureau,  1897. 
RAINFALL  AND  FLOW  OF  STREAMS.  C.  C.  Babb.  Trans.  Am.  Soc.  C.  E.,  vol.  28,  p.  329,  1894. 
THE  INFLUENCE  OF  FORESTS  UPON  THE  RAINFALL  AND  UPON  THE  FLOW  OF  STREAMS.  G.  F.  Swain. 

Jour.  New  Eng.  W.  Wks.  Ass'n. 
DATA  OF  STREAM  FLOW  IN  RELATION  TO  FORESTS.     G.  W.  Rafter.    Ass'n  C.  E.  Cornell  Univ.,  vol.  7, 

p.  22,  1899. 

THE  CONSERVATION  OF  WATER.     John  B.  Freeman.     Proc.  Am.  Inst.  E.  E.,  March  24,  1909. 
THE  WASTES  OF  OUR  NATURAL  RESOURCES  BY  FIRE.     Charles  Whiting  Baker.     Proc.  Am.  Inst.  E  E., 

March  24,  1909. 
ELECTRICITY  AND  THE  CONSERVATION  OF  ENERGY.     Lewis  B.  Stillwell.     Proc.  Am.  Inst.  E.  E., 

March  24,  1909. 


CHAPTER   II. 
DAMS. 

Gravity  Dams.  The  fundamental  principles  on  which  the  stability  of  a  dam  is 
calculated  are  given  in  the  following  formulas:  First,  it  is  essential  to  know  the 
location  of  the  center  of  gravity  of  a  dam.  This  may  be  found  for  a  dam  of  triangular 
shape,  as  it  is  indicated  in  Fig.  i.  Assuming  that  the  water  behind  the  dam  is  even 


FIG.  i. 

with  the  crest,  as  seen  in  Fig.  2,  the  pressure  of  the  water  against  the  dam  is  calculated 
in  the  following  way: 

H  =  head  or  height  in  feet. 

P  =  total  pressure  of  water  in  pounds. 

H  ( 

—  =  center  of  pressure. 

3 

W  =  total  weight  of  dam  acting  through  center  of  gravity, 


P  =H  X  i  X  62.5  X—  • 

2 

The  pressure,  P,  acts  perpendicularly  to  the  face,  and  in  turning  the  dam  over 
uses  the  lever  AD.     The  overturning  moment  is  P  X  DA. 

19 


20 


HYDROELECTRIC    DEVELOPMENTS   AND   ENGINEERING. 


To  counterbalance  the  tendency  of  the  water  to  overturn  the  dam,  the  weight 
of  the  dam  acts  through  the  lever  AF.  EF  is  drawn  perpendicular  to  the  base 
through  the  center  of  gravity.  The  resisting  moment  due  to  the  weight  of  the  dam 

is  W  X  FA. 

Wx  FA 

-  is  the  factor  of  safety. 
P  X  DA 


H 


w 


FIG.  3. 


When  the  dam  is  turned  around  as  shown  in  Fig.  3,  the  stability  is  calculated  as 
follows : 

The  water  pressure  acts  perpendicularly  to  the  face  CB,  and  the  center  of  pressure 
acts  on  a  line  at  the  intersection  of  the  slope  and  J  H. 

The  force,  P,  tends  to  overturn  the  dam  about  A  with  a  lever  arm  DA,  which  is 
the  perpendicular  distance  between  the  line  of  application  of  P  and  the  point  A. 
From  this,  it  will  be  noticed,  that  the  flatter  the  face  CB,  the  less  tendency  the  water 
has  to  overturn  the  dam. 

W  X  FA 


P  X  DA 


is  the  factor  of  safety. 


By  examining  the  above  fraction  it  will  be  seen  that  the  factor  of  safety  is  increased. 
That  is,  as  the  dam  is  made  to  approach  the  gravity  type,  the  overturning  tendency 
of  the  water  is  diminished. 

The  above  calculations  are  based  on  a  theoretical  dam,  such  as  is  never  built, 
because  it  is  impractical  to  build  such  a  sharp  crest,  owing  to  the  flow  of  water.  In 
practice,  gravity  dams  are  built  similar  to  Fig.  4;  the  center  of  gravity  is  found  by 
laying  off  the  breadth  of  the  base  on  the  slope  side  of  the  crest,  and  the  breadth  of 
the  crest  on  the  opposite  side  on  the  base;  then  draw  a  line  connecting  the  points  W. 


DAMS. 


21 


Draw  a  line  from  the  middle  of  the  crest  to  the  middle  of  the  base,  connecting 
points  XY.  The  center  of  gravity  is  located  at  the  intersections  of  lines  UV  and  XY. 
As  gravity  dams  usually  have  water  flowing  over  (Fig.  5),  the  following  calculations 


FIG.  4. 


FIG.  5. 


represent  the  conditions  to  be  considered.  The  center  of  gravity  is  found  as  in 
Fig.  4.  The  vertical  line  EF  is  drawn  through  the  center  of  gravity.  The  pressure 
P  acts  at  point  Z,  and  is  located  according  to  the  formula 

7_H/  _h_ 

~  3  V1      H  +  2  h 

The  overturning  effect  of  the  water  is  the  same  as  before,  P  X  AD.  The  dam 
counterbalances  the  overturning  effect  of  the  water  with  a  moment,  W  X  FA. 


W  X  FA 
P  X  AD 


—  factor  of  safety. 


IR  is  the  resultant  of  forces  P  and  W,  and  is  found  by  the  application  of  paral 
lelogram  of  forces.     IW  is  drawn  proportional  to  the  weight  of  the  masonry,  and 
WR  is  drawn  proportional  to  the  pressure  of  the  water.     To  have  the  dam  stable, 
the  resultant,  IR,  must  cut  the  base  in  some  point  as  K,  which  must  be  at  a  distance 
greater  than  one-third  the  length  of  the  base  from  the  toe. 

The  downstream  side  or  face  of  the  spillway  of  the  dam  must  be  made  to  conform 
with  the  shape  of  the  overflowing  water,  and  in  order  to  prevent  erosion,  the  foot 
must  be  provided  with  a  curved  apron  as  seen  in  the  accompanying  illustrations 
(Figs.  6  to  8).  This  apron  must  be  designed  to  withstand  the  effect 'of  vacuum 
produced  by  the  overflowing  water. 


22 


HYDROELECTRIC    DEVELOPMENTS    AND    ENGINEERING. 


Earthen  and  timber  dams  have  long  upstream  faces,  so  that  the  tendency  for  the 
water  to  overturn  them  is  greatly  lessened,  and  are  more  fully  treated  under  their 
respective  sub-headings. 


FIG.  6. — Cross  Section  of  Dam  (St.  Louis 
River).  Great  Northern  Power  Company, 
Duluth,  Minnesota. 


FIG.  7. — Dam  at  Morgan  Fall,  Georgia. 
Chattahoohee  River. 


Masonry  Dams.  Masonry  dams  are  made  either  in  the  gravity  or  arch  type. 
The  stability  of  the  straight  gravity  dam  depends  upon  its  own  weight,  while  that  of 
the  arch  type  depends  upon  the  thrust  action  at  the  ends,  which  rest  on  the  mountain 
slope. 

All  gravity  dams  must  rest  upon  very  solid  foundations.  Where  this  condition 
cannot  be  obtained,  an  artificial  one  must  be  made,  which  can  be  done,  for  instance, 
by  driving  wooden,  concrete  or  iron  sheet  piles.  Where  a  rock  bed  is  found,  the  bed 
must  be  cleaned  of  all  earth  and  loose  boulders,  and  provided  with  trenches  to  increase 

the  resistance  of.  friction  by  sliding.  The  bottom 
of  the  dam  should  extend  some  five  or  six  feet 
below  the  river  bed  to  prevent  the  water  from 
leaking  under,  which  might  make  the  dam  fail. 

The  majority  of  masonry  dams  are  made  of 
solid  concrete  or  of  cyclopean  masonry  (Fig.  8). 
The  mixture  used  in  concrete  dams  is  1:3:6 
or  i  :  4  :  8,  depending  greatly  upon  the  size  of  the 
dam.  Frequently  a  coarser  mixture  is  used, 
known  as  rubble  concrete.  In  large  hydraulic 
undertakings,  particularly  in  the  West,  cyclopean 
masonry  is  employed ;  the  stones  vary  in  size  from 
cobble-stones  up  to  stones  weighing  one  to  two  tons. 
The  stones  are  so  placed  that  the  smaller  ones  fill 


FIG.  8. — Dam  at  Spier  Fall,  Albany. 
Hudson  River  Electric  Power 
Company,  New  York. 


up  the  places  between  the  big  ones,  the  whole  being  embedded  in  concrete  mortar. 
Care  must  be  taken  in  the  construction  of  these,  as  well  as  other  dams,  to  make  them 


A.E.&M. 


DAMS.  23 

*    «   H  I 

as  water  tight  as  possible  to  prevent  seepage.  To  accomplish  this,  the 
side  of  the  dam  must  be  faced  with  a  rich  mixture  of  cement  mortar  or  a  finer  course 
of  concrete;  sometimes  tiles  are  used  for  facing.  In  addition  to  this,  vertical  drain- 
age pipes  are  embedded  in  the  concrete  to  carry  off  seepage.  The  pipes,  usually 
4  inches  in  diameter,  are  set  in  vertical  sections,  with  space  between,  so  that  the 
seepage  can  enter  same,  and  join  mains  which  discharge  on  the  downstream  side. 

Reinforced  Concrete  Dams.  In  the  last  five  or  six  years,  the  reinforced  concrete 
dam  has  been  much  favored  for  hydroelectric  plants.  The  design  is  specialized  and 
involves  striking  features  of  the  adaptability  of  reinforced  concrete.  The  principle, 
which  these  designers  of  dams  endeavor  to  preserve,  is,  that  the  water  pressure  applied 
to  a  dam  renders  it  not  less  but  more  stable,  that  is,  the  vertical  component  of  the 
static  pressure  is  made  use  of  to  pin  the  dam  to  its  foundations,  whereas,  with  the 
previously  discussed  masonry  gravity  dams,  the  pressure  of  the  water  is  exerted 
horizontally  (provided  the  upstream  side  is  vertical)  to  overturn  the  dam,  which  must 
therefore  be  made  sufficiently  massive  to  resist  the  pressure  by  its  own  weight.  The 
pressure  exerted  on  the  foundation  of  a  gravity  dam  varies,  theoretically,  from  zero 
at  the  upstream  edge  to  a  maximum  at  the  downstream  edge.  The  maximum  must 
never  exceed  the  crushing  strength  of  the  material.  Usually  a  factor  of  safety  of  2-  or 
i  A  is  employed. 

The  slope  of  the  "deck"  of  a  reinforced  concrete  dam  may  be  so  related  to  the 
weight  and  width,  that  the  pressure  on  the  foundation  is  controlled  at  the  will  of  the 
designer. 

Usually  the  proportions  are  such  that  the  diagram  of  pressure  is  nearly  a  rectangle; 
i.e.,  the  pressure  is  kept  substantially  uniform  over  the  whole  foundation,  and  with  the 
excess  pressure,  if  any,  thrown  slightly  towards  the  upstream  angle  instead  of  being 
concentrated  at  the  downstream  edge.  This  arises  from  the  fact  that  the  resultant 
of  the  water  pressure  and  weight  of  the  dam  can  be  held  at,  or  a  little  above,  the  center 
of  the  base,  instead  of  passing  down  to  the  lower  edge  of  the  middle  third.  The 
movements  of  this  resultant  and  the  base  pressures  dependent  thereon  may  be  followed 
in  the  diagram,  Fig.  9,  in  which  the  resultant,  as  the  dam  fills,  is  seen  to  advance 
slightly  upstream  from  the  center,  until  the  dam  is  about  three-quarters  full,  returning 
again  nearly  to  the  center,  when  the  dam  is  under  its  calculated  flood.  The  angle  of 
the  resultant  also  is  always  kept  within  the  limit  of  the  angle  of  friction,  so  that  the 
dam  has  no  tendency  to  move  on  its  base. 

Fig.  10  shows  about  the  simplest  form  of  dam  adapted  to  moderate  heads  and 
hard  foundations.  It  consists  of  a  series  of  buttresses  variously  spaced  from  12  feet 
to  18  feet  apart  on  centers,  and  covered  with  a  deck  of  concrete,  reinforced  between 
the  different  bays  as  a  beam  after  the  usual  formula.  The  factor  of  safety  throughout 
is  said  to  be  never  less  than  5  in  all  its  relations.  But  little  reinforcement  is  used  in 
the  buttresses,  except  at  the  edges  and  around  the  openings,  which  are  left  for  con- 
venience and  to  save  material.  The  deck  reinforcement,  however,  is  abundant,  and 
is  within  i|  inches  of  the  lower  side,  leaving  from  10  inches  to  several  feet  of  concrete 
between  the  steel  and  the  water.  The  thickness  of  the  deck  necessarily  increases 
from  top  to  bottom  with  the  increase  of  head.  The  concrete  in  the  deck  is  mixed 


Of  CA. 


24 


HYDROELECTRIC    DEVELOPMENTS    AND   ENGINEERING. 


FIG.  9. — Behavior  of  Resultants  in  Solid  Dam. 


W5  10  Flood 


FIG.  10. — Behavior  of  Resultants  in  a  Concrete-Steel  Dam. 


DAMS.  25 

1:2:4,  usually  with  fine  aggregates,  and  is  poured  into  the  forms  in  the  condition 
known  as  "  slop  concrete."  This  insures  a  thorough  coating  of  the  steel  with  cement, 
and  furthermore,  insures  a  density  of  concrete  which  seems  to  be  sufficient  to  forestall 
porosity  altogether. 

A  dam  of  this  design,  when  on  rock,  has  no  continuous  base,  and  therefore  cannot 
be  threatened  by  water  pressure  finding  its  way  through  seams  in  the  rock,  and 
exerting  a  lifting  pressure  on  the  dam.  On  gravel  or  other  porous  foundations,  an 
artificial  base  is  first  laid  down  covering  the  entire  area,  but  in  such  cases,  this  base 
or  floor  is  pierced  with  numerous  "weep  holes,"  so  that  upward  pressure  is  again 
forestalled. 

Being  hollow,  reinforced  concrete  dams  not  only  possess  the  unusual  feature  of 
interior  inspection,  but  the  hollow  space  puts  at  the  disposal  of  the  engineer  a  valuable 
space  from  which  to  work  the  various  adjuncts,  such  as  flashboards,  waste  gates, 
log  sluices,  movable  crests,  etc.,  all  of  which  are  handled  from  the  inside  of  the  dam, 
allowing  the  whole  width  of  the  river  to  be  utilized  for  rollway,  instead  of  being 
more  or  less  obstructed  by  bulkheads.  The  interior  of  the  dam  admits  of  plenty  of 
space  for  a  passageway,  which  may  vary  from  an  ordinary  foot  bridge  to  the  equip- 
ment of  a  complete  power  plant  as  seen  in  Fig.  n. 


FIG.  ii. — Patapco  Dam,  Ilchester,  Maryland. 

The  spacing  of  the  piers,  which  leaves  a  free  waterway,  often  enables  this  type  of 
dam,  on  certain  foundations,  to  be  built  without  the  use  of  a  coffer  dam,  by  first 
carrying  up  piers  in  caissons  to  a  uniform  grade  a  few  feet  above  the  ordinary  water 
level,  and  then  completing  the  superstructure  while  the  water  is  allowed  to  run 
freely  between  the  piers.  When  the  dam  is  completed,  these  spaces  are  subsequently 
and  permanently  closed  with  concrete. 

Referring  to  Fig.  .11,  this  dam,  200  feet  long  and  30  feet  high,  is  located  near 
Ilchester,  Md.,  and  crosses  the  Patapsco  River.  The  power  house  is  located  inside, 


26  HYDROELECTRIC    DEVELOPMENTS   AND   ENGINEERING. 

and  is  equipped  with  three  5oo-HP.  turbines,  provided  with  draft  tubes  extending 
vertically  into  the  tailrace;  the  generators  are  direct  connected  to  the  turbines;  the 
switchboard  and  other  electrical  equipment  are  also  located  inside,  so  that  the  whole 
plant  is  housed  inside  of  the  dam.  As  this  plant  has  been  in  operation  for  some  time, 
no  trouble  has  been  experienced  due  to  moisture;  however,  the  power  house  itself  is 
inclosed  with  four-inch  walls  of  ferro-inclave,  entirely  separate  from  the  structure  of 
the  dam  itself. 

Another  power  plant,  where  a  reinforced  concrete  dam  has  been  employed,  is  given 
in  Fig.  12,  showing  the  general  arrangement  of  dam,  forebay  and  power  house,  of 
the  Bar  Harbor  and  Union  River  Power  Company,  Ellsworth,  Me.  The  dam  is 
450  feet  long  and  64  feet  high.  The  conditions  were  such,  that  a  semi-attached  power 
house  was  necessary  at  right  angles  to  the  dam,  and  necessarily  supplied  from  a 
forebay.  Access  to  the  power  house  and  waste  gates  may  be  had  through  the  body  of 
the  dam,  which  is  entered  on  the  opposite  end  from  the  power  house.  Part  of  the 
dam  is  utilized  as  a  machine  shop,  storeroom,  etc.  A  sluice  gate  in  the  crest  is 
provided,  to  flush  away  the  accumulated  trash  which  may  lodge  against  the  dam. 
The  details  of  construction  of  the  dam  are  given  in  Figs.  13  and  14,  and  are  self- 
explanatory. 

This  dam,  as  well  as  those  above  described,  was  constructed  by  the  Ambursen 
Hydraulic  Company,  Boston,  Mass.,  to  whom  the  writer  is  indebted  for  data  on 
reinforced  concrete  dams. 

Coffer  Dams.  In  most  cases,  when  dams  are  built,  coffer  dams  are  necessary  to 
hold  back  the  water,  so  that  the  construction  of  the  main  dam  can  be  carried  on. 
The  coffer  dams  are  built  so  that  a  section  of  the  stream  or  the  entire  river  is  deflected. 

They  are  temporary  constructions,  and  are  removed  after  the  main  dam  is  com- 
pleted. In  shallow  and  still  water,  they  may  be  built  of  gravel  and  clay,  or  bags 
filled  with  gravel  and  clay,  or  bundles  of  fagots,  between  which  is  placed  gravel  and 
clay.  When  the  water  is  deeper  and  a  current  exists,  this  material  is  apt  to  be 
washed  away;  in  such  a  case,  sheet  piling  is  used.  Where  single  sheet  piling  is  not 
sufficient  to  withstand  the  current,  two  rows  of  sheet  piling  are  used,  the  space  between 
being  filled  with  puddle;  this  construction,  of  course, ., has  to  be  properly  braced,  and, 
as  it  is  composed  mostly  of  wood,  it  is  becoming  very  expensive;  owing  to  this  fact,  it 
has  been  replaced  in  recent  years  by  sheet  steel  piling.  This  sheet  steel  piling  is 
made  of  rolled  iron,  such  as  Z-bars,  channels,  I-beams,  and  in  some  cases,  specially 
rolled  forms;  they  are  so  placed  that  they  are  interlocked  and  kept  water  tight.  This 
system  is  very  much  favored,  particularly  in  large  construction  work.  They  are 
easily  driven  home,  and  after  the  work  is  finished,  they  may  be  used  again  for  other 
or  similar  purposes. 

Crib  Dams.  Where  the  bed  of  the  river  is  rock  or  near  to  it,  the  sheet  pile  coffer 
dam  cannot  be  used;  in  place  of  it,  the  crib  dam  must  be  substituted.  Before  a  crib 
is  sunk,  soundings  must  be  made,  to  ascertain  the  contour  of  the  bottom;  in  some 
cases  divers  are  sent  down.  The  lower  part  of  the  crib  is  made  on  shore  and  floated 
to  the  place  where  it  is  to  be  sunk,  which  is  done  by  filling  the  same  with  rocks.  As 
the  crib  sinks,  the  remainder  of  the  crib  is  completed.  These  cribs  are  made  in 


DAMS. 


>> 

CU 


c 
.2 
°e 
P 


PQ 


< 

o  • 


I 


I 

0) 

bo 


O 


28 


HYDROELECTRIC    DEVELOPMENTS    AND    ENGINEERING. 


:J2"< 


'•torizontal  Wafer  Pre$s..< 
~  2,376,570  lbs.~per  15%. 


\       \«v   .   weracre  Pressure  =  165  Ibs.  oersa'.in.     '  Offset  El.  ?.5~" 


EN&.  NEWS. 


\  Top  of  Dft    »IZ"< 

W-^3'l 

''n  Buttress  No.17. 


Openings  shown  in 

Full  Lines  made  in 

"  V  Buttresses  Jtvfc 


v":::  ""'££'<?."  •-'•          "<"'"ffW/ 
-;J—  --<;; 


«^;g^ 
FIGS.  13  and  14. — Detail  Construction  of  Reinforced  Concrete  Dam  at  Ellsworth,  Maine. 


DAMS. 


29 


sections,  about  8  to  10  feet  square,  and  are  grouped  in  width  according  to  the  height 
of  the  crib.  The  opening  between  adjoining  cribs  must  be  closed  up  by  stop  logs 
and  timber  sheeting. 

The  sheeting  must  be  placed  so  as  to  break  joints,  and  shaped  to  fit  the  profile 
of  the  river  bed.  For  further  tightness,  riprap,  sand  and  loam  are  dumped  on  the 
bottom  of  the  upstream  side  of  the  crib. 


;x»  "*"*•£•> 
1  3£*£| 


FIG.  15. — Coffer  Dam. 


FIG.  16.— Timber  Dam. 

Timber  Dams.  In  a  timber  gravity  dam,  the  timbers  are  placed  alternately 
parallel  to  and  crosswise  the  stream,  the  spaces  between  being  filled  with  earth  and 
stone.  The  bearings  of  the  timbers  are  either  notched,  or  spiked  by  iron  drift  bolts. 
If  the  dam  is  built  for  retaining  water  only,  the  upstream  side  is  built  on  a  slope, 
while  the  downstream  side  may  be  vertical.  If  the  water  overflows  the  dam,  the 
downstream  side  must  be  on  a  slope,  in  order  to  prevent  the  water  washing  away  the 
river  bed  in  front  of  the  dam.  There  are  several  examples  of  failures  of  timber  dams 
due  to  the  erosion  of  the  river  bed.  Trautwine  states: 1  the  Jones  Dam  at  Cape  Fear 

1  Trautwine,  Civil  Engineers'  Pocket  Book. 


30  HYDROELECTRIC    DEVELOPMENTS   AND   ENGINEERING. 

River  had  a  height  of  16  feet,  and  the  usual  water  fall  was  10  feet  into  a  pool  6  feet 
deep,  and  in  a  few  years  wore  out  the  soft  shale  rock,  undermining  the  dam  to  such  an 
extent  that  it  gave  way.  The  timber  dam  at  Holyoke  is  another  example  of  the 
erosion  of  the  river  bed  due  to  the  falling  of  the  water,  so  that  the  dam  had  to  be 
reinforced  by  a  downstream  apron. 

The  apron  of  the  downstream  side  of  the  dam  should  be  on  an  angle  of  about 
30  degrees,  so  that  the  water  has  an  easy  overflow  and  protects  the  river  bed. 

There  are  other  forms  of  timber  dams, ,  the  frame  types.  They  are  built  in 
framework  of  various  forms,  which  vary  according  to  conditions.  The  timbers  are 
framed  and  strongly  braced,  upon  the  top  of  which  is  placed  sheet  planking.  As  they 
are  lighter  than  the  rock-filled  timber  dam,  the  upstream  side  must  be  on  a  longer 
slope,  so  that  advantage  may  be  taken  of  the  weight  of  the  water  to  secure  greater 
stability.  These  dams  are  easily  built,  and  in  certain  sections  of  the  country  they 
are  the  cheapest  form  for  hydraulic  power  developments. 

However,  with  the  diminution  of  the  forests  and  the  cheapness  of  masonry  and 
iron,  the  latter  is  more  profitable  to  use. 


FIG.  17. — Hauser  Lake  Steel  Frame  Dam. 

Steel  Frame  Dams.  Similar  in  construction  to  the  timber  framework  dam  is 
the  steel  frame  dam,  as  seen  in  Fig.  17.  This  dam  has  been  erected  by  the  Helena 
Power  Transmission  Company,  across  the  Missouri  River  at  Helena,  Mont.1 
During  a  period  of  the  year,  about  two  to  four  months,  it  has  to  stand  high  floods 
and  act  as  an  overflow  dam.  It  is  about  75  feet  high  and  630  feet  long.  The  lower 
section  of  the  upstream  side  is  of  concrete,  behind  which  is  rubble  masonry;  the  upper 
section  is  made  of  structural  steel  trusses  9  feet  9  inches  apart.  The  entire  upstream 
side  is  faced  with  steel  plates;  those  on  the  bottom  extend  into  concrete  and  fasten 
to  sheet  piling  beneath  the  river  bed,  so  as  to  prevent  the  water  from  washing  beneath 

1  Zeitschrift  des  Vereines  deutscher  Ingenieure,  April  18,  1908. 


DAMS.  31 

the  dam.  These,  as  well  as  those  on  the  upper  section,  are  flat  plates,  five-sixteenths 
of  an  inch  thick,  while  the  middle  are  concave  and  three-eighths  inch  thick.  Only 
the  upper  section  of  the  downstream  side  is  faced  with  steel  plates;  the  lower  section 
is  made  of  timber  and  faced  with  planking.  On  the  top  of  the  dam  is  a  flashboard 
structure  faced  with  steel  plates  at  both  ends,  and  in  the  middle  is  an  opening  50  feet 
long  to  let  through  floods,  and  can  be  closed  after  the  flood  has  passed. 

This  dam  failed  on  April  14,  1908,  and  at  the  time  of  the  accident,  the  matter 
of  acceptance  and  final  settlement  was  in  the  hands  of  the  attorneys  of  the  power 
company.  The  following  is  an  abstract  report  given  by  the  Electrical  Review.1 

''The  initial  break  occurred  at  bent  39,  about  400  feet  from  the  east  or  power- 
house end  of  the  dam.  The  anchorage  at  this  point  apparently  gave  way,  breaking 
the  seal,  and  allowing  the  water  to  pass  under  the  rubble  masonry  fill.  The  water 
rapidly  cut  away  the  gravel,  permitting  settlement  of  this  upstream  masonry,  and 
carrying  down  with  it  the  lower  end  of  the  girder,  forming  the  upper  member  of  the 
steel  bent.  The  expansion  joint  in  this  girder,  and  in  the  plates  of  the  dam  just  above 
the  top  of  the  masonry,  gave  way,  leaving  the  bents  and  plates  unsupported  in  such 
a  manner  that  the  water  pressure  pushed  over  this  section.  About  six  minutes 
elapsed  from  the  time  the  water  first  came  through  under  the  rubble  masonry  until 
the  expansion  joint  failed  and  the  first  bent  toppled  over,  carrying  out  a  section 
about  30  feet  in  width.  The  tremendous  rush  of  water  rapidly  widened  the  breach, 
the  foundations  on  each  side  were  undermined,  and  the  posts  and  steelwork  buckled 
at  right  angles  to  the  direction  of  the  flow  of  the  river.  The  bents  continued  to  give 
way  and  fall  until  the  breach  widened  to  nearly  300  feet." 

Earth  Dams.  The  earth  dam  is  the  oldest  type  of  dam  known,  and  is  still  used  in 
hydraulic  developments.  They  are  made  of  loam,  clay,  and  rock,  or  a  combination 
of  same.  These  dams  are  used  principally  in  still  water;  however,  if  they  are  intended 
to  be  used  as  an  overflow  dam,  they  must  be  properly  faced  so  that  no  erosion  can 
take  place.  The  upstream  side  usually  has  a  slope  of  2  :  i,  while  the  downstream 


i 

*&d&&&&<§Kffi^$&  'i    ft®  ^  •"' " ' ;""'  K'"'k  "  ^%s 

KV,-  '••^•.-.•^ ^.^^^:,  n ivi™--;,- \z&--:-:'M*-&:&i. 


jBau^g^ji^^p^d^KS  ^^^m^^^^ 

FIG.  18. — Cross  Section  of  Necaxa  Dam,  Mexico. 

• 

side  has  the  same  slope  or  somewhat  less,  frequently  i£  :  i.  These  dams  are  some- 
times sluiced  into  place.  A  dam  built  after  this  method  is  given  in  Fig.  18;  it  is  that 
of  the  Necaxa  Light  and  Power  Company.2  It  is  180  feet  high,  1276  feet  long  at 
the  crest,  and  has  a  thickness  of  950  feet  at  the  base  and  54  feet  at  the  top.  The 

1  Electrical  Review,  May  16,  1908.  J  Trans.  Am.  Soc.  C.  E.,  vol.  LVIII,  p.  37,  1907. 


32  HYDROELECTRIC    DEVELOPMENTS    AND    ENGINEERING. 

slope  on  the  upstream  side  {83:1,  and  on  the  downstream  side  2:1.  The  make-up 
of  the  dam  is  best  shown  in  the  cut,  and  consists  of  about  2  million  cubic  yards  of 
material,  which  was  obtained  from  the  neighboring  hills  and  sluiced  into  place. 

The  method  of  construction  as  given  in  a  paper,  "The  Necaxa  Plant  of  the 
Mexican  Light  and  Power  Company,"  by  F.  S.  Pearson  and  F.  O.  Blackwell,  is  as 
follows: 

"The  ground  was  first  cleared  and  stripped,  a  trestle  to  support  the  flume  was 
erected,  and  low  earth  dikes  were  made  at  the  upstream  and  downstream  limits  of 
the  fill,  to  hold  the  mud  and  water.  The  material  was  then  sluiced  in,  the  pipes 
discharging  near  the  embankments  so  that  the  boulders  and  gravel  were  deposited 
on  the  faces,  and  the  fine  mud  in  the  center  of  the  dam.  The  dikes  were  raised  as 
the  dam  filled,  and  the  water  spilled  over  the  upstream  face  into  the  pond.  During 
construction  the  water  of  the  river  passed  through  the  discharge  gates,  which  were 
made  large  enough  for  the  purpose.  A  spillway  was  provided  over  a  neck  of  rock 
to  the  north  of  the  dam." 

For  additional  stability,  the  earth  dam  may  be  built  with  a  concrete  or  reinforced 
concrete  core.  A  dam  of  the  latter  type  is  at  Dixville,  N.H.1  The  core,  1:3:4 
concrete,  is  3  feet  thick  at  the  bottom  and  10  inches  at  the  top;  it  is  reinforced  by 
corrugated  steel  bars.  Owing  to  the  character  of  the  soil  the  core  rests  on  an  inter- 
locking steel  sheet  piling,  which  is  driven  at  depths  ranging  from  10  to  32  feet,  the 
entire  length  of  the  dam,  the  upper  end  being  embedded  into  the  concrete  core. 


25'----* 

f  I 


FIG.  19. — Earth  Dam  with  Reinforced  Concrete  Core  Wall,  Dixville,  New  Hampshire. 

Movable  Dams.  There  are  great  variations  in  movable  dams,  such  as  sluice  gate, 
drum  and  butterfly  types,  and  common  flashboards.  They  are  used  where  a  great 
fluctuation  of  water  level  is  encountered,  and  are  adapted  to  establish  various  heads. 
Probably  the  most  prominent  of  this  type  of  dam  is  the  Stoney  roller  sluice  gate, 
built  in  practically  any  size.  These  gates  move  in  vertical  grooves  on  roller  trains  in 
the  abutting  piers.  The  arrangement  of  the  roller  trains  is  such  that  the  gates  move 
twice  as  fast  as  the  rollers,  that  is,  the  gates  roll  on  the  diameter  of  the  rollers,  and 
the  rollers  roll  on  their  radii;  both  the  rollers  and  the  gates  are  counterbalanced,  so 

1  An  Earth  Dam  with  Reinforced  Concrete  Core  Walls  at  Dixville,  N.H  ,  by  A.  W.  Dudley.  Engineer- 
ing Record,  April  25,  1908. 


DAMS. 


33 


f«t«Ji  ;  / 
\  ''•'->*  ;  - 
?,i:  l'-tl; 

•fli^-fyssj 


i  ; !    ';&<<' ' ! 


FIG.  20. — General  Arrangement  of  Stoney  Roller  Sluice  Gate,  at  Beznau  Plant, 

Switzerland. 


34 


HYDROELECTRIC    DEVELOPMENTS    AND   ENGINEERING. 


that  a  gate  under  a  pressure  of  300  or  400  tons  can  be  easily  moved  by  hand.  A 
type  of  this  gate  is  shown  in  Fig.  20,  seven  of  which  have  been  installed  in  connection 
with  the  Beznau  plant,  Switzerland. 

These  gates  are  49  feet  wide  and  20  feet  high;  they  are  made  of  structural  steel, 
and  provided  on  the  bottom  with  a  square  timber,  resting  on  a  cast-iron  shoe  embedded 
in  the  concrete  of  the  dam.  The  sides  of  the  gates  are  made  water  tight  by  steel 
ropes  which  are  held  against  the  joint  by  the  pressure  of  the  water  (see  Fig.  21). 


FIG.  21. — Details  of  Stoney  Roller  Sluice  Gate. 


Each  gate  may  be  operated  by  hand,  two  men  being  necessary,  or  for  quick  operation, 
there  is  a  portable  8-HP.  motor.  Plans  are  at  present  in  preparation  for  the  installa- 
tion of  an  hydraulic  turbine  at  the  dam,  for  automatically  operating  these  gates  in 
case  of  emergency.  The  discharge  of  the  water  from  this  type  of  dam  takes  place 
from  underneath  as  the  dam  is  hoisted;  thus  the  foreign  material  which  collects  on 
the  bottom  is  easily  discharged. 

Butterfly  Dam.  Another  type  of  movable  dam  is  the  butterfly,  an  example  of 
which  is  given  in  Fig.  22.  Two  of  this  kind  have  been  installed  in  connection  with 
the  Chicago  Drainage  Canal,1  one  being  12  feet  and  the  other  48  feet  wide. 

The  two  movable  crest  dams  are  practically  alike  in  details  of  construction  and 
operation.  Each  movable  crest  is  built  of  structural  steel  shapes  and  steel  plates, 
and  is  practically  a  45-degree  sector  of  a  cylinder  with  a  26-foot  radius.  Each  sector 
is  hinged  horizontally  along  the  axis  of  the  cylinder  of  which  it  would  form  a  part,  to 

1  Movable  Crest  Dams  at  the  Water  Power  Development  of  the  Chicago  Drainage  Canal.  The 
Engineering  Record,  Aug.  24,  1907. 


DAMS. 


A.E.&M.i 

UNlV.  OF  CA 

The  radial          '"~" 


the  top  of  a  back  wall  on  which  it  is  mounted  on  the  downstream  side, 
deck  plane  and  the  curved  upstream  front  of  the  sector  are  made  water  tight  with 
steel  plates,  the  deck  being  provided  with  steel  angles  for  ice  skids.  The  deck  plane, 
the  lower  radial  plane  and  the  curved  face'  are  heavily  reinforced  by  intermediate 
steel  frames.  When  the  crest  formed  by  the  intersection  of  the  curved  face  and  the 
radial  deck  plane  is  at  the  maximum  operating  height,  the  lower  radial  plane  of  the 
sector  is  horizontal.  As  the  crest  is  lowered,  the  sector  rotates  on  its  axis  and  moves 


FIG.  22. — Butterfly  Dam,  Chicago. 
Drainage  Canal  Power  Plant. 


FIG.  23. — Detail  of  Back  Hinge  of 
Butterfly  Dam. 


into  a  space  in  the  concrete  base,  which  is  also  approximately  a  sector  of  a  cylinder, 
of  about  the  same  radius  as  that  of  the  crest,  the  radial  deck  being  horizontal  when 
the  crest  is  at  its  lowest  position.  The  crests  of  both  dams  have  a  vertical  range  of 
18  feet,  from  2  feet  above  to  16  feet  below  Chicago  datum,  the  water  surface  above  the 
dams  being  4  to  6  feet  below  that  level  under  normal  conditions  of  flow. 

Bear  Traps.  The  old  bear-traps  consisted  of  two  leaves,  hinged  to  the  foundations. 
The  upstream  leaf  overlaps  the  downstream  leaf  when  the  gate  is  lowered.  A  culvert 
leaves  from  the  river  upstream,  to  the  space  under  the  leaves,  and  a  second  culvert 
from  this  space  to  the  river  downstream,  and  are  provided  with  valves.  When  the 
first  culvert  is  opened  with  the  second  closed,  the  hydraulic  pressure  under  the  leaves 
causes  them  to  rise,  provided  the  head  from  the  upstream  culvert  is  sufficient. 
Reversing  the  process,  the  leaves  will  fall. 

The  interior  angle  formed  by  the  leaves  in  the  raised  position  must  not  be  less 
than  90  degrees,  since,  if  it  were,  the  trap  when  once  up,  would  not  fall  under  the 
action  of  the  hydraulic  forces.  The  angle  should  be  about  100  to  105  degrees,  and 
if  the  angle  is  too  great,  the  width  of  the  base  will  be  excessive  in  proportion  to  the 
height  of  the  crest  above  the  foundations. 

The  principal  defects  of  the  old  bear-trap,  as  given  by  P.  S.  Bond,1  are  as  follows: 

I.  Sliding  friction  between  the  leaves. 

II.  Width  of  base  too  great  for  height  attained. 

III.  The  overlap  of  upper  upon  lower  leaf. 

IV.  Inability  to  raise  and  fall  uniformly  (tendency  to  warp). 

1  The  Permanent  Improvement  of  the  Ohio  River.     The  Engineering  Record,  Jan.  16,  1909. 


36  HYDROELECTRIC    DEVELOPMENTS    AND   ENGINEERING. 

V.  Necessity  for  initial  head  in  raising. 

VI.  Difficulty  of  stopping  without  shock  in  raising. 

VII.  Difficulty  of  operation  in  wide  passes,  and  division  into  several  sections 
by  piers. 

VIII.  Leakage  at  time  of  raising. 

IX.  Liability  of  binding  on  debris  along  side  walls,  and  driftwood  lodged  in 
the  exterior  angle  between  the  leaves. 

X.  Improper  proportioning  of  leaves  (unscientific  design). 

XL  Cost. 

Many  improvements  have  been  made  in  late  years,  which  relate  more  or  less  to 
the  mechanical  construction. 

Cylindrical  Dams.  On  the  continent  of  Europe,  several  cylindrical  rolling  dams 
have  been  installed.  Two  prominent  ones  are  located  in  the  rivers  Main  and  Sau 
at  Schweinfurt,  Bavaria;1  the  former  is  13.5  feet  in  diameter  and  has  a  clear  width 
of  about  60  feet;  the  other  one  has  a  diameter  of  6.5  feet  and  a  length  of  115  feet. 
It  is  practical  to  make  them  39  feet  in  diameter  and  150  feet  span.  These  dams  are 
nothing  more  than  two  concentric  shells,  the  space  between  being  air  tight.  The  inner 
shell  is  open  at  the  ends,  so  that  when  the  dam  is  lowered,  the  water  flows  through, 
thus  reducing  the  buoyancy  effect.  The  dam  is  raised  and  lowered  by  a  chain  or 
cable  wound  around  one  end;  both  ends  roll  on  cogwheel  tracks. 

The  principal  claims  for  this  type  of  dam  are,  the  elimination  of  piers  in  the  center 
of  a  river,  simplicity  of  construction  in  dam  as  well  as  machinery,  and  ease  of  opera- 
tion. The  dam  may  be  easily  raised  above  the  river  level,  thus  giving  a  free  and 
unobstructed  passage. 

Needle  Dams.  A  system  for  the  temporary  impending  of  water  is  the  needle 
dam,  consisting  of  a  row  of  squared  timber  or  heavy  planking  set  upright  against  a 
trestle.  In  case  of  excessive  flood,  a  number  are  removed  and  the  water  released. 
As  these  needle  dams  are  usually  built  across  the  entire  width  of  the  river,  the  trestle 
remains  as  an  obstruction  to  floating  material  when  any  of  the  needles  are  removed. 

Chanoine  Dam.  The  objection  in  the  needle  dam  mentioned  is  overcome  in  the 
Chanoine  Dam,  which  can  be  lowered,  thus  giving  free  passage;  it  will  tip  auto- 
matically when  the  water  rises  to  a  certain  height  overflowing  the  crest,  similar  to 
permanent  flashboards. 

The  movable  parts  of  the  Chanoine  Dam  consist  of  a  row  of  wickets  hinged  on 
horses,  and  held  in  place  by  props.  A  detailed  description  of  this  system  will  be 
found  in  The  Engineering  Record.2 

Flashboards.  In  order  to  take  care  of  surplus  water  during  flooding  periods,  or 
minimum  use  of  water,  flashboards  are  employed  to  impend  water  for  dry  season, 
or  maximum  demand.  They  are  designed  to  withstand  a  certain  amount  of  water, 
which  would  otherwise  discharge  over  the  dam;  should  the  pressure  exceed  the 
designed  limit,  the  supports  give  way  and  the  boards  are  washed  downstream; 

1  Wegmann,  The  Design  and  Construction  of  Dams. 

*  Permanent  Improvement  of  the  Ohio  River      P.  S.  Bond.     The  Engineering  Record,  Jan.  9,  1909. 


DAMS.  37 

this  of  course  in  most  instances  would  mean  the  loss  of  planking.  However,  in 
many  instances,  heavy  floods  are  anticipated,  and  the  flashboards  are  removed 
before  the  flood  reaches  its  height. 

Permanent  flashboards  are  so  arranged  that  part  or  the  whole  are  removed,  should 
the  water  rise  above  the  limit.  They  may  be  built  of  structural  steel;  placed  and 
removed  from  a  footpath  carried  above  the  dam. 

Another  type  of  flashboard  is  of  structural  steel  held  in  an  upright  position  by 
rods  hinged  below  the  center  of  the  board.  When  the  pressure  of  the  water  above 
the  hinge  exceeds  that  exerted  against  the  flashboard  below  the  hinge,  the  flashboard 
drops  over  automatically;  it  is  not  washed  away,  but  held  by  the  anchor  rods. 

Fishways.  Fishways  are  frequently  required  in  connection  with  dams,  in  order 
to  provide  a  passage  for  fish  which  return  upstream  to  their  breeding  places  during 
certain  seasons  of  the  year.  In  most  countries,  it  is  specified  by  the  government 
whether  they  have  to  be  installed  or  not;  the  size  of  these  fishways  depends  upon  the 
kind  of  fish  and  their  habits;  data  on  this  subject  can  be  obtained  from  the  govern- 
ments as  well'as  local  authorities. 


FIGS.  24  and  25. — Types  of  Fishways. 


These  fishways  are  always  located  on  one  side  of  the  dam,  the  outlets  being  at  the 
bottom  of  the  dam,  because  the  fish  usually  gather  there.  The  principle  of  a  fishway 
consists  in  retarding  the  velocity  of  the  water  in  an  inclined  trough  provided  with 
obstructions,  so  that  the  mean  velocity  will  be  no  more  than  6  or  8  feet  per  second, 
with  resting  places  made  by  the  nature  of  the  obstructions.  Such  a  passage,  in  most 
cases,  is  nothing  more  than  a  series  of  steps  forming  cascades,  between  which  are 
pools  of  water  as  indicated  in  Fig.  25.  Another  form  of  fishway  is  seen  in  Fig.  26; 
it  is  nothing  more  than  a  chute  which  reduces  the  velocity  of  the  water  by  the  friction 
of  a  zigzag  course.  These  fishways  are  made  either  of  wood  or  masonry. 


38  HYDROELECTRIC    DEVELOPMENTS   AND    ENGINEERING. 

BIBLIOGRAPHY. 

THE  DESIGN  AND  CONSTRUCTION   OF  DAMS.     Edward  Wegmann.     1899.     John  Wiley    &   Sons. 

New  York. 
RESERVOIRS  FOR  IRRIGATION,  WATER  POWER  AND  DOMESTIC  WATER  SUPPLY.     James  Dix  Schuyler. 

1901.     John  Wiley   &  Sons.     New  York. 

MASONRY  CONSTRUCTION.     I.  O.  Baker.     1903.     John  Wiley  &  Sons.     New  York. 
NOTES  ON  STRESSES  IN  MASONRY  DAMS.     Max  aus  Ende.     Engineering,  Dec.  8,  1905. 
INTERNAL  STRESSES  IN  MASONRY  DAMS.     S.  D.  Bleich.    School  of  Mines  Quarterly,  November,  1905. 
RECENT  PRACTICE  IN  HYDRAULIC-FILL  DAM  CONSTRUCTION.     J.  D.  Schuyler.     A.  S.  C.  E.,  October, 

1906. 

MASONRY  DAMS.     Th.  G.  Bocking.     Engineering,  Sept.  27,  1907. 
MASONRY  DAM  FORMULAS.     Orin  L.  Brodie.     School  of  Mines  Quarterly,  April,  1908. 
THE  DESIGN  OF  BUTTRESSED  DAMS  OF  REINFORCED  CONCRETE.     R.  C.  Beardsley.    Engineering 

News,  April  23,  1908. 
A  FORMULA  FOR  CALCULATING  FLASHBOARDS  FOR  DAMS.     Richard  Muller.    Engineering  Record, 

Aug.  22,  1908. 

THE  DESIGN  OF  RETAINING  WALLS.     Harold  A.  Petterson.     Engineering  Record,  June  13,  1908. 
A  PROPOSED  NEW  TYPE  OF  MASONRY  DAM.     Geo.  L.  Dillman.     Trans.  A.  S.  C.  E.,  vol.  49,  p.  94, 

1902. 
THE  CORRECT  DESIGN  AND  STABILITY  OF  HIGH  MASONRY  DAMS.    Geo.  Y.  Wisner.    Engineering 

News,  Oct.  i,  1903. 

ON  THE  STABILITY  OF  MASONRY  DAMS.    Karl  Pearson.    Aug.  n,  1905. 
ON  THE  DISTRIBUTION  OF  SHEARING  STRESSES  IN"  MASONRY  DAMS.    W.  C.  Unwin.    Engineering, 

June  30,  1905. 

THE  STRESSES  ON  MASONRY  DAMS.    Engineering,  September,  1907. 
DESIGN  OF  AMERICAN  DAMS.     Engineering  Record,  Feb.  20,  1902. 
THE  LIMITING  HEIGHTS  OF  EARTH  DAMS.    Engineering  Record,  Dec.  7, 1901. 
EARTH  DAMS  WITH  CONCRETE  CORE  WALLS.    Engineering  News,  Sept.  7,  1905. 
RECENT  PRACTICE  IN  HYDRAULIC- FILL  DAM  CONSTRUCTION.     Proc.  Am.  Soc.  C.  E.,  October,  1906. 
A  COLLAPSIBLE  STEEL  DAM  CREST.     J.  C.  Wheeler.     Engineering  News,  Oct.  3,  1907. 
A  NEW  AUTOMATIC  MOVABLE  DAM.     Engineering  Record,  March  8,  1902. 
MOVABLE  DAMS.     B.  F.  Thomas.     A.  S.  C.  E.,  March,  1898. 

AMERICAN  TYPES  OF  MOVABLE  DAMS.     Hiram  M.  Chittenden.     Engineering  News,  Feb.  7,  1895. 
MOVABLE  DAMS,  SLUICE  AND  LOCK  GATES  OF  THE  BEAR-TRAP  TYPE.    Archibald  O.  Powell.    Jour- 
nal Association  Engineering  Societies,  June,  1896. 


CHAPTER    III. 
HEADRACE. 

Scheme.  The  arrangement  of  headrace  is  governed  entirely  by  natural  conditions. 
While  some  plants  require  a  dam  only,  for  securing  water  supply,  others  require  in 
addition,  miles  of  headrace,  including  expensive  tunneling  and  installation  of  high- 
pressure  penstocks.  These  are  the  extremes  between  high  and  low  head  plants. 
The  ultimate  aim  in  both  cases  is,  to  secure  the  greatest  amount  of  energy  with  least 
expenditure  both  in  first  cost  and  cost  of  operation.  Therefore,  the  building 
containing  the  turbines  should  be  located  so  as  to  utilize  the  most  efficient  head. 
In  some  cases,  tailrace  water  is  discharged  directly  into  the  headrace  of  a  plant 
located  below. 


FIG.  i. — Typical  General  Arrangement  of  a  Hydroelectric  Development. 

Fig.  i  illustrates  a  way  of  harnessing  a  stream  and  conducting  the  water  to  the 
power  house,  or,  in  short,  a  complete  hydraulic  installation.  In  connection  with 
same,  the  tailrace  of  a  previously  installed  plant  is  utilized.  This  particular  plant 
has  been  selected  because  it  contains  most  of  the  features  to  be  met  in  harnessing 

39 


40  HYDROELECTRIC    DEVELOPMENTS   AND   ENGINEERING. 

water  for  hydroelectric  developments.  It  utilizes  the  water  of  the  river  Sill,  and 
supplies  the  capital  of  Tyrol,  Innsbruck,  with  light  and  power. 

In  the  illustration,  the  letter  C  designates  the  tailrace  of  a  6ooo-HP.  plant,  a,  which 
joins  the  headrace  at  the  sluice  gates  h;  g  are  sluice  gates  to  control  the  water  in 
the  river;  e  is  a  spillway  dam;/ and /represent  racks;  one  prevents  foreign  material 
from  entering  the  entrance  basin  from  the  river,  and  the  other,  a  finer  one,  prevents 
material  from  entering  from  the  headrace.  At  the  lower  end  of  the  entrance  basin  is 
a  sandtrap  designated  by  k;  there  is  also  a  sandtrap  k  at  the  side  of  the  sluice  gate  /, 
before  the  water  enters  the  tunnel;  i  is  a  spillway  in  the  flume  to  discharge  surplus 
water.  The  letters  m  designate  shafts  leading  to  the  headrace  tunnel,  which  is  4.7 
miles  long.  There  are  seven  shafts  in  all.  The  tunnel  has  a  slope  of  i  foot  in  1000. 
It  takes  one  hour  for  the  water  to  travel  from  the  entrance  basin  to  the  collecting 
reservoir.  The  letter  n  is  an  overflow  wall  in  the  reservoir,  while  p  is  a  sluice  for 
emptying  same. 

The  water  is  discharged  down  the  mountain  slope,  in  cascade  to  break  the  fall, 
and  joins  the  tailrace  n.  As  the  plant  is  located  in  a  district  of  frequent  and  heavy 
snowfalls,  a  snow  sluice  o  is  provided.  The  water,  before  entering  the  penstock  r, 
must  pass  through  a  fine  screen/  then  through  a  sluice  g. 

While  the  velocity  of  the  water  in  the  tunnel  is  7.4  feet,  the  velocity  in  front  of 
the  screens,  before  entering  the  penstocks,  is  only  i  foot  per  second.  At  the  bottom 
of  the  screen,  which  sets  on  the  skew,  is  another  sandtrap  which  discharges  into  the 
cascade. 

It  will  be  noticed  that  there  is  only  one  penstock  r  in  place,  to  supply  three  units; 
it  is  about  11,000  feet  long,  and  laid  on  the  mountain  at  an  angle  of  33  degrees.  The 
head  is  602  feet  to  the  center  of  the  turbine  shaft.  As  the  friction  loss  is  5.5  feet, 
the  effective  head  is  596.5  feet. 

The  penstock  is  made  up  of  steel  plates  in  sections,  and  the  diameter  is  4.1  feet, 
the  upper  section  being  of  five-sixteenths  material,  and  the  lower  section  thirteen- 
sixteenths  inch. 

The  turbines  are  of  the  impulse  type,  mounted  in  pairs  on  one  shaft;  when 
running  at  350  R.P.M.  and  with  an  efficiency  of  80  per  cent  they  develop  2500  H.P., 
and  consume  45.4  cubic  feet  of  water  per  second. 

CONDUITS. 

Water  may  be  conducted  by  the  following  methods: 

1.  Canals. 

2.  Tunnels. 

3.  Penstocks. 

The  canals  may  be  subdivided  into  trenches  and  flumes. 

The  tunnels  may  be  non-pressure  and  pressure. 

The  penstocks  always  operate  under  pressure,  and  may  be  built  of  steel,  wood 
or  reinforced  concrete. 

Cross  Section  of  Canals.  The  cross-section  area  of  a  canal,  may  it  be  a  trench 
or  flume,  should  be  such  that  the  water  will  rise  to  about  three-quarters  to  seven- 


HEADRACE. 


eighths  of  the  height,  but  should  never  be  higher  than  the  latter.  The  rectangular 
form  is  the  most  common  one  in  use,  and  is  so  proportioned  that  the  depth  of  the 
water  is  about  half  of  the  width.  The  slope  of  the  canal  depends  on  the  degree  of 
smoothness  of  the  bottom,  and  varies  from  one-half  to  one  foot  in  a  thousand;  the 
latter  is  more  common. 

Trenches.  The  most  common  form  of  canal  is  an  open  trench  dug  in  the  soil, 
and  the  sides  sloped  according  to  the  firmness  of  the  soil,  usually  i  :  i.  If  loose 
soil  is  encountered,  the  form  of  the  canal  must  be  such  that  the  velocity  is  about 
2  to  3  feet  per  second.  If  a  higher  velocity  is  taken,  the  sides  and  bed  will  be  disturbed. 
If  good  loam  is  found,  the  velocity  may  be  taken  as  4  feet  per  second.  This  may 
be  increased  to  4.5  to  5  feet  by  lining  the  sides  and  bottom  with  paving  stone  and 
gravel. 

According  to  Bazin's  formula,  the  bottom  and  mean  surface  velocity  may  be 
found  as  follows: 

v  —  max.  v  —  25.4  \/rs\  v  =  vb  +  10.87  \/rs\  .'.  vb  =  v  —  10.87  ^^s. 
v  =  mean  velocity  in  feet  per  second. 
max.  v  =  maximum  surface  velocity  in  feet  per  second. 
vb  =  bottom  velocity  in  feet  per  second. 
r  =  hydraulic  mean  depth  in  feet  =  area  of  cross  section  in  square  feet 

divided  by  wetted  perimeter  in  feet. 
s  —  sine  of  slope. 

The  lowest  velocity  is  found  in  the  wetted  perimeter.  The  different  velocities, 
according  to  Rankine,  are  in  the  ratio  2  :  3  :  4  in  low-velocity  canals,  and  3  :  4  :  5  in 
high-velocity  canals.  The  greatest  velocity  is  found  in  the  middle  slightly  below  the 
surface. 

Ganguillet  and  Kutter  give  the  following  table  I,  of  safe  bottom  and  mean  veloci- 
ties in  channels^  calculated  from  the  formula, 


v  = 


10.87 


The  results  obtained  by  using  this  formula  are  very  low,  as  admitted  by  the  above 
authorities. 

TABLE    I  —  WATER    VELOCITY    IN    CHANNELS. 


Material  of  channel. 

Safe  bottom  velocity 
(vt)  in  feet  per 
second. 

Mean  velocity 
(v)  in  feet  per 
second. 

Soft  brown  earth  ...    

o.  249 

o.  328 

Soft  loam  

O    4OO 

o.  6s6 

Sand  

I    OOO 

I  .  312 

Gravel  .        

I   908 

2.621; 

Pebbles  

2.  OOO 

3.918 

Broken  stone,  flint  

4  .  OO'3 

c.  cyo 

Conglomerate,  soft  slate  

4.988 

6.  ^64 

Stratified  rock  

6.006 

8.  204 

Hard  rock  .        

10.  009 

IV  127 

42 


HYDROELECTRIC    DEVELOPMENTS   AND    ENGINEERING. 


The  following  figures  are  selected  from  a  diagram  by  W.  A.  Burr *  showing  the 
resistance  of  various  soils  to  erosion  by  flowing  water. 

TABLE    II. —  MAXIMUM    WATER    VELOCITY    IN    CHANNELS. 


Material. 

Velocity  in  feet 
per  second. 

Pure  sand  

I.  I 

Sandy  soil,  15  per  cent  clay  

I.  2 

Sandy  loam,  40  per  cent  clav  

1.8 

Loamy  soil,  65  per  cent  clav  

3.  o 

Clay  loam    85  per  cent  clay.  .                 .        

4.8 

Agricultural  clay   05  per  cent  clav                      .... 

6    2 

Clav  

7.  1$ 

Masonry  Flumes.  Flumes  are  made  either  of  masonry  or  of  planking.  The 
former  resembles  the  trench,  but  has  vertical  walls.  They  may  be  made  of  brick, 
concrete  or  reinforced  concrete. 

Those  made  of  concrete  are  the  most  common  ones  in  use,  and  usually  follow  the 
contour  of  the  ground.  If  concrete  flumes  have  to  cross  valleys,  either  filling  has  to 
be  made  or  else  solid  pier  construction  has  to  be  used,  in  a  way  similar  to  the  old 
Roman  aqueducts,  in  which  case  reinforced  concrete  may  be  successfully  employed. 
The  wetted  perimeter  must  be  smooth,  so  as  to  allow  a  velocity  of  7  to  8  feet  per 
second.  The  bottom  must  have  a  slope  of  one-half  to  one  foot  in  a  thousand. 

As  an  example  of  modern  concrete  flume  construction,  the  one  of  the  Kern  River 
Power  Plant  is  cited:  The  whole  structure  is  carried  on  1 5-inch  I-beams  set  8  feet 
10  inches  apart,  supported  by  concrete  piers.  These  longitudinal  girders  carry 
9-inch  steel  I-beams  laid  transversely  4  feet  center  to  center,  and  on  them  is  erected 
a  framework  of  structural  steel  for  the  sides  and  bottom  of  the  flume.  Two  layers 
of  expanded  metal  of  1.5  and  3-inch  mesh  are  used  in  connection  with  this  framework, 
and,  being  embedded  in  concrete,  form  the  sides  inclosing  the  frame.  This  concrete 
construction  is  also  reinforced  on  the  floor  by  twisted  half-inch  rods.  The  outside 
and  inside  of  the  flumes  are  plastered,  making  the  thickness  of  the  reinforced  concrete 
sides  and  bottom  4  inches. 

This  type  of  flume  or  conduit,  while  it  costs  more  than  a  wooden  flume,  has  the 
advantage  of  being  as  permanent  as  tunnels  themselves. 

Wooden  Flumes.  Wooden  flumes,  which  are  used  mostly  in  the  West  and  Pacific 
Coast,  are  constructed  of  California  fir,  redwood  and  Oregon  pine.  They  are  best 
carried  on  trestlework  or  concrete  piers,  and  are  usually  of  the  open  type,  and  built 
on  a  slope  of  one-half  to  one  foot  in  a  thousand.  The  planking  must  be  laid  so  that 
the  pieces  break  joints.  The  wetted  perimeter  must  be  smooth  to  allow  a  velocity 
of  7  to  8  feet  per  second.  They  must  be  water  tight,  which  may  be  done  as  given 
in  an  example  below.2 


1  Engineering  News,  Feb.  8,  1894. 

3  Kern  River  Power  Plant  No.  i,  by  C.  W.  Whitney.     The  Engineering  Record,  Aug.  10,  1907. 


HEADRACE. 


43 


With  the  installation  of  this  plant,  there  are  five  wooden  flumes/ the;  longest  being 
1030  feet,  the  shortest  being  50  feet.  They  are  placed  on  concrete  'foundations, 
and  are  designed  with  a  factor  of  safety  sufficient  to  make  their  life  from  30  to  40  years. 
The  framework  for  supporting  the  flume  box  is  of  Oregon  pine,  being  so  designed  and 
distributed  that  no  part  of  the  timber  comes  in  contact  with  the  earth,  or  is  exposed 
to  the  drip  should  the  flume  at  any  point  spring  a  leak.  The  flume  box  is  built  up 
of  3  by  12-inch  redwood  planks  obtained  from  butt-ends  of  Sequoia  Semper  Virens, 
grown  in  swamp  lands  west  of  the  coast  range  of  northern  California. 

The  grain  of  this  lumber  is  perfectly  clear,  and  its  quality  is  such  that  its  life 
should  not  be  less  than  forty  years.  The  edges  of  all  planks  were  beveled  so  as  to 
give  a  one-quarter  inch  opening  on  the  inside  of  the  joints,  which  is  calked  with 


FIG.  2. — Detail  of  a  Timber  Flume,  32-foot  Span. 

ship-chandler's  oakum.  The  bottom  seams  were  covered  with  hot  asphaltum  and 
i  by  6-inch  redwood  battens  nailed  down  over  them.  On  the  sides  of  these  flumes 
a  specially  designed  batten  is  used.  This  batten  is  of  i  by  6-inch  redwood,  the  upper 
half  being  cut  away  on  a  curve,  permitting  asphaltum  to  be  poured  between  the  batten 
and  the  side  of  the  flume.  At  the  corners  of  the  flumes  a  quarter-round  strip  is  nailed 
(Fig.  2). 

The  design  of  the  flume  above  described  has  been  thoroughly  tested,  and  even 
if  it  should  stand  dry  for  months  in  the  hottest  weather,  the  designers  stated  that  it 
may  be  again  filled  with  water  without  having  any  perceptible  leakage. 

In  some  of  the  flumes  where  streams  are  crossed  that  are  apt  to  carry  considerable 


44 


HYDROELECTRIC    DEVELOPMENTS    AND    ENGINEERING. 


•AM  ixv'i'h.  winter, 'span  flumes  are  constructed.  One  of  these  span  flumes  has  a  length 
of  32  feet,  built 'with  a  10  by  12-inch  timber  frame,  resting  on  12  by  i2-inch  beams. 
In  connecting  the  wooden  flume  with  the  portal  of  a  tunnel,  a  construction  of  a  special 
nature  was  used,  which  offers  two  points  of  contact  between  the  wood  and  the  con- 
crete, and  a  well  between  the  two,  from  which  the  water  may  be  pumped  out,  and 
any  leaks  repaired  should  these  ever  occur  between  the  wood  and  the  concrete. 

,Wiro  nails 


FIG.  3. — Timber  Flume,  on  Mountain  Slope.     American  River  Electric  Company. 

Protection  of  Flumes.  Frequently  the  flumes  run  on  the  sides  of  mountain  slopes, 
and  are  endangered  by  loose  boulders.  Where  flumes  pass  through  such  sections, 
they  should  be  provided  with  some  means  of  protection.  One  way  of  protecting  the 
flumes  is  to  build  a  retaining  wall  of  sufficient  height  on  the  mountain  side  of  the 
flume,  to  deflect  the  boulders  across  same.  Another  way  is  to  cover  the  flume  with 
concrete  slabs,  preferably  reinforced  with  rods.  Where  loose  boulders  or  land-slides 
are  severe,  the  cover  should  have  an  arch  form,  and  in  any  case,  should  be  covered 
with  at  least  two  feet  of  earth  to  act  as  a  cushion. 


HEADRACE.  45 

Tunnels.  As  stated,  tunnels  for  hydraulic  developments  are  classified  as  non- 
pressure  and  pressure  tunnels.  In  the  former  case,  the  tunnel  is  only  partly  filled, 
and  in  the  latter,  it  is  completely  filled  and  under  pressure  due  to  the  head  of  the 
water.  The  cross  section  of  the  tunnel  may  be  semi-egg-shaped,  or  rectangular 
with  an  arched  roof.  Where  the  tunnels  run  through  loose  soil,  they  must  be  lined, 
the  thickness  of  which  varies  with  the  character  of  the  soil  and  the  pressure  required 
to  retain  same.  The  lining  may  be  made  of  brick,  but  in  later  years,  concrete  has 
been  used  exclusively.  Where  there  is  a  possibility  of  a  cave-in,  they  must  preferably 
be  reinforced  with  rods.  The  cross  section  should  be  uniform  throughout,  except 
near  the  collecting  reservoir,  so  that  it  may  serve  as  an  additional  storage.  They 
are  usually  built  with  a  slope  of  i  to  2  feet  in  1000,  and  have  a  velocity  of  7  to  8  feet 
per  second.  Where  the  tunnel  is  several  miles  long,  it  is  advisable  to  provide  at  every 
mile,  access  to  same;  this  is  usually  done  by  vertical  shafts.  In  cases  where  overflow 
side-tunnels  are  provided,  these  shafts  may  be  eliminated. 

Pressure  Tunnels.  In  the  last  few  years  several  plants  have  been  installed  with 
pressure  tunnels,  particularly  in  Europe.  These  tunnels  are  thoroughly  and  strongly 
lined,  and  as  water  tight  as  possible,  because  they  are  under  pressure.  Such  tunnels 
are  provided  with  a  vertical  shaft,  the  upper  end  of  which  is  enlarged  to  serve  as  an 
air  chamber  and  absorb  fluctuations.  One  of  the  most  notable  examples  making 
use  of  this  system,  is  that  of  the  Urfttalsperre  installation,  Germany.  This  plant  is 
operating  under  a  head  varying  from  230  to  360  feet.  At  the  end  of  a  885o-foot 
tunnel  is  located  the  vertical  or  equilizer  shaft.  The  top  of  this  shaft,  sunk  through 
the  mountain,  is  higher  than  the  high-water  level  in  the  reservoir,  so  as  to  prevent, 
in  case  of  sudden  shut-down  of  the  plant,  a  waste  of  water.  It  will  be  seen  from  this, 
that  the  equilizer  shaft  acts  as  a  standpipe,  similar  to  those  installed  on  penstocks. 
These  shafts  are  more  economical  than  standpipes  because  they  do  not  waste  the 
water. 

With  exceptionally  long  pressure  tunnels,  it  is  advisable  to  install  vent  pipes  along 
the  line,  to  let  out  air  which  might  collect,  and  prevent  same  from  getting  into  the 
penstock. 

Friction  in  Tunnels.  In  order  to  minimize  friction  in  tunnels,  the  perimeter  must 
be  smooth,  which  is  accomplished  by  a  cement  coating.  In  case  of  non-pressure 
tunnels,  the  coating  should  extend  some  6  inches  above  the  highest  water  level; 
while  in  pressure  tunnels,  the  coating  must  extend  over  the  whole. of  the  interior 
surface.  Where  the  tunnel  is  cut  through  hard  rock,  and  a  smooth  surface  is  easily 
obtainable,  the  lining  may  be  omitted  and  only  a  coating  provided.  This  coating 
has  to  fill  up  small  recesses  in  the  rock,  and  to  face  the  concrete  lining.  It  is  made 
of  a  mixture  of  one  part  sand  and  two  of  cement,  and  applied  about  a  quarter  of 
an  inch  thick. 

Another  way  to  reduce  friction,  is  to  have  the  course  of  the  tunnel  as  straight  as 
possible;  short  radius  curves  must  be  avoided.  Where  the  side  walls  join  the  bottom, 
the  junction  must  be  a  smooth  curve. 

Seepage  in  Tunnels.  Where  tunnels  run  through  mountains  and  seepage  water 
is  encountered,  provision  must  be  made  to  take  care  of  same.  In  high-pressure 


46 


HYDROELECTRIC    DEVELOPMENTS    AND    ENGINEERING. 


tunnels,  this  trouble  amounts  to  little  or  nothing,  especially  as  these  tunnels  have 
to  be  constructed  as  water  tight  as  possible.  In  non-pressure  tunnels  overflow  devices 
may  overcome  the  difficulty.  These  overflow  devices  are  nothing  more  than  overflow 
weirs,  discharging  into  side  tunnels  taking  the  shortest  cut  to  the  mountain  slope. 
Fig.  4  shows  such  a  device,  as  installed  in  the  Brusio  Power  Plant,  Switzerland.  The 
tunnel  of  this  installation  is  1756  feet  long,  built  on  a  slope  of  2  feet  in  1000,  and 


FIG.  4. — Overflow  Device  in  Headrace  Tunnel,  Brusio  Plant,  Switzerland. 

is  provided  with  u  overflow  devices.  It  will  be  noticed  that  the  main  tunnel  is  only 
partly  lined.  In  connection  with  same,  the  horsepower  carrying  capacity  is  indicated; 
of  course  this  capacity  applies  only  to  this  particular  plant. 

Construction  of  Tunnels.  In  the  construction  of  long  tunnels,  which  in  some 
cases  represent  the  greatest  expenditure  in  hydroelectric  engineering,  temporary 
power  plants  are  installed,  particularly  when  plants  are  remote  from  power  supply. 
Tunnels  are  usually  begun  at  both  ends,  arid  in  some  cases  at  intermediate  places, 
where  shafts  have  been  driven.  Where  intermediate  junctions  are  to  be  made,  and 
the  character  of  soil  is  known,  and  varies  from  rock  to  soft  earth,  the  junctions  are 
best  made  at  such  places. 

For  cutting  rock,  pneumatic  or  electric  drills  are  employed;  two  or  more  drills  are 
mounted  on  a  truck  running  on  rails.  Where  the  tunnel  is  driven  through  loam, 
special  cutting  machines  which  run  on  tracks  may  be  employed.  Cases  sometimes 
arise,  particularly  in  Switzerland,  where  the  tunnels  have  to  be  cut  under  pressure; 
when  such  is  the  case,  it  is  customary  to  heavily  line  the  tunnel  as  fast1  as  the  work 
proceeds. 

Siphon  System.  In  some  installations,  in  order  to  utilize  the  water  of  a  mountain 
lake,  the  bottom  of  same  has  to  be  tapped,  for  which  purpose  sheet  piling  is  driven. 


A.E.&M.E 


HEADRACE.  47 

The  tapping  of  a  lake  on  the  bottom  is  very  troublesome,  particularly  "when  the 
soil  is  soft,  and  might  cause  failure  in  construction.  Swiss  engineers,  in  such  a  case, 
have  adopted  the  siphoning  system,  which  consists  of  sinking  a  vertical  shaft,  a  safe 
distance  from  the  shore  of  the  lake,  to  which  the  headrace  tunnel  is  connected.  The 
water  is  siphoned  from  the  lake  into  the  shaft.  One  leg  of  the  siphon  is  submerged 
in  the  shaft,  and  the  other  is  carried  on  a  trestle  out  into  the  lake,  and  extends  down 
into  same  as  far  as  possible,  to  take  advantage  of  all  the  water  available. 

To  the  author's  knowledge,  the  first  siphon  system  installed  was  that  of  the  Kubel 
plant,  and  the  largest  one,  in  connection  with  the  Brusio  plant,  both  in  Switzerland. 


TT  "77 

FIG.  5. — Siphon  System  at  Lake  Poschiavo. 

An  illustration  of  the  latter  is  given  in  Fig.  5.  The  siphon  tube  is  6.5  feet  in  diameter 
and  is  made  of  /g-inch  material. 

As  it  is  submerged  below  the  normal  water-bed  of  the  lake,  it  will  start  automati- 
cally. The  horizontal  part  of  the  siphon  is  placed  on  a  slope  of  i  :  1000,  and  has,  at 
the  highest  point,  two  pipe  connections,  one  3.5-inch  for  air  pump  and  the  other  an 
8-inch  centrifugal  pump  connection.  If  for  any  reason  the  siphon  should  stop 
operating  and  the  water  level  is  low,  either  of  the  pumps  may  reestablish  the  siphoning 
action. 

Both  ends  of  the  siphon  are  provided  with  controlling  valves.  In  addition  to 
this,  the  suction  leg  has  a  one-inch  mesh  screen,  which  may  be  cleaned  by  breaking 
the  siphon,  and  allowing  the  water  to  flow  back,  or  the  centrifugal  pump  may  be 
applied  to  same. 

RACKS    AND    GATES. 

Racks.  There  are  two  different  kinds  of  racks,  one  in  which  the  bars  are  spaced 
far  apart,  and  the  other  where  they  are  near  together.  The  former  is  known  as 
rack,  the  latter  as  screen.  The  racks  must  be  placed  at  the  entrance  to  the  forebay 
or  the  entrance  to  headrace,  in  order  to  keep  the  heavy  floating  material  out.  In 
small  plants,  these  racks  are  made  in  sections,  so  that  they  may  be  easily  removed 
and  cleaned.  In  large  plants,  the  racks  are  stationary  and  are  made  of  heavy  bars, 


48 


HYDROELECTRIC    DEVELOPMENTS    AND   ENGINEERING. 


or  sometimes  light  I-beams,  all  depending  upon  the  force  with  which  the  floating 
material  acts  on  the  racks.  No  round  bars  or  pipes  should  be  used  for  this  purpose, 
although  the  latter  is  sometimes  used. 

Racks,  made  of  round  material,  will  collect  more  foreign  matter  than  flat  or 
square  bars,  because  the  latter  deflect  better  than  the  former.  Further,  it  is  more 
troublesome  to  clean  racks  with  round  bars  than  with  flat  ones,  as  the  wedge  action 
of  floating  material  is  greater  with  round  than  with  flat  bars.  The  space  between 
the  bars  should  not  be  less  than  1.5  inches,  and  should  never  exceed  4  inches.  This 


FIG.  6.  —  Screen  House,  Plant  No.  2,  Niagara  Falls  Power  Company. 


is  particularly  true  when  the  racks  are  placed  at  the  entrance  of  a  long  inclosed  head- 
race, otherwise  deflectors  must  be  installed,  to  deflect  material  which  passes  the 
outside  racks.  If  this  is  not  done,  there  is  a  possibility  of  the  headrace  becoming 
clogged.  Racks  may  be  set  vertically  or  at  an  angle,  as  long  as  the  facility  for  clean- 
ing is  not  sacrificed.  Bars  3.5  by  0.5  inches,  bolted  together  with  separators,  give 
a  suitable  construction  for  average  conditions. 

In  plants  where  heavy  material  has  to  be  deflected  from  the  headrace,  an  arrange- 
ment-similar to  Figs.  7  and  8  might  be  adopted.  It  is  a  combined  regulating  device, 
rack  and  deflector,  and  has  been  installed  in  the  headrace  of  the  Hafslund  Power 
Plant,  Norway.  As  this  is  made  of  heavy  I-beams,  much  clearance  is  allowed. 
Any  material  which  passes  the  openings  is  prevented  from  entering  the  penstocks  by 
two  other  racks,  one  rough  and  one  fine.  The  former  is  in  front  of  the  forebay  and 
provided  with  a  sandtrap;  the  latter  is  directly  in  front  of  the  penstocks. 


HEADRACE. 


49 


As  is  seen  in  Fig.  8,  there  are  two  water  levels,  which  are  controlled  by  hoisting 
or  lowering  the  I-beam  rack.  Even  if  the  gate  is  open,  the  elevations  will  differ, 
owing  to  the  deflector  extending  some  19  feet  into  the  water.  In  certain  seasons 
of  the  year,  the  rack  is  lowered  so  that  anchor  ice  will  either  be  broken  up  on  the  rack, 
or  forced  upward  and  deflected  by  the  wall.  Because  the  width  of  the  headrace  is 
32.8  feet,  it  is  necessary  to  split  the  rack  into  sections,  to  facilitate  handling.  By 


">v^       ^^\ 

FIGS.  7  and  8. — Deflector  and  Rack  in  Headrace,  Hafslund  Plant,  Norway. 

means  of  a  windlass,  which  travels  on  a  bridge,  the  different  sections  are  hoisted 
and  fastened  to  the  latter.  This  serves  a  twofold  purpose:  first,  reducing  the  weight 
to  be  lifted;  second,  the  regulation  of  the  water  is  better  accomplished. 

Screens.  Screens  are  frequently  made  of  2  by  f-inch  bars.  They  are  spaced  from 
f  to  |  inch  apart.  These  screens,  in  almost  all  cases,  are  made  in  sections,  with  the 
exception  of  those  at  small-sized  plants;  even  then,  two  screens  are  provided,  so  that 
when  one  is  being  cleaned  the  other  is  lowered.  Such  is  seen  in  Figs.  3  and  4,  which 
gives  the  general  arrangement  as  well  as  construction.  It  will  be  noticed  that  there 
are  two  screens  hoisted  and  lowered  by  a  windlass.  There  is  a  walkway  supported 
on  brackets  in  front  of  the  upper  screen,  so  that  the  attendants  may  have  free  access 
for  cleaning.  The  lower  end  of  the  bars  of  the  rear  screen  are  bent,  so  that  when  the 
screen  is  hoisted,  the  floating  material  goes  with  it. 


50  HYDROELECTRIC    DEVELOPMENTS   AND   ENGINEERING. 

It  is  advisable  to  place  screens  on  an  angle  from  45  to  60  degrees;  this  not  only 
brings  submerged  floating  material  to  the  surface,  but  adds  greatly  to  the  passage 
area  of  the  screen,  and  reduces  the  velocity  of  water.  Such  screens  are  arranged  in 
one  row,  so  as  to  cover  a  number  of  penstock  inlets;  they  are  divided  into  sections, 
horizontally  and  vertically,  and  slide  in  vertical  guides  made  of  cast  iron  or  rolled 
steel  channels.  When  they  are  divided  into  vertical  sections,  they  overlap  each  other 


FIG.  9. — Arrangement  of  Screen  and  Vent  of  Penstock  Inlet. 

for  several  inches;  they  are  arranged  so  that  one  or  more  sections  may  be  hoisted 
independently  of  the  others.  By  extending  the  abutments,  the  partition  walls  of 
the  turbine  chambers  provide  a  very  suitable  support;  otherwise  they  will  have  to 
be  braced  from  the  rear  with  structural  steel;  this  of  course  depends  on  the  size  of 
the  screen.  Theory  shows,  that  when  the  bars  of  the  screen  occupy  one-quarter 
of  the  area  of  the  water  inlet  to  the  turbine  chamber,  the  drop  in  head  due  to  resistance 
is  from  2.5  to  3.5  per  cent.1 

Wooden  Sluice  Gates.    For  controlling  the  water  supply  in  the  headrace,  usually 
vertical  moving  sluice  gates  are  employed.     The  small  sizes  up  to  100  square  feet 

1  Gelpke,  Turbinen  und  Turbinenanlagen,  p.  142. 


HEADRACE. 


are  made  of  wood,  while  the  larger  ones  are  made  of  structural  steel.  If  conditions 
favor  the  use  of  large  wooden  sluice  gates,  they  must  be  cut  up  into  sections,  other- 
wise they  will  be  too  bulky.  The  sections  may  be  split  up  either  vertically  or  hori- 


;!:.nt      I   • 


FIG.  10. — Detail  of  Screen. 

zontally.  In  the  former  case,  more  guide?  are  necessary,  and  as  a  single  sluice  gate 
extends  through  the  entire  depth  of  the  water,  the  water  flows  underneath  the  gate. 
In  the  latter  case,  fewer  guides  are  necessary,  and  the  waste  may  flow  through  the 
bottom,  middle  or  upper  sluice  gate.  Besides  this,  the  individual  stages  of  such 


52  HYDROELECTRIC    DEVELOPMENTS   AND   ENGINEERING. 

types  do  not  have  to  withstand  the  total  head.  Furthermore,  this  type  of  sluice  gate 
is  advantageously  used  in  connection  with  sandtraps  and  overflows,  particularly 
for  ice.  They  may  also  be  used  as  an  adjustable  weir,  but  in  such  cases  they  are 
usually  made  of  structural  steel. 


FIG.  ii. — Wooden  Sluice  Gate.     Hand  and  Motor  Operated. 

For  calculating  stresses  in  wooden  sluice  gates,  the  table  on  the  following  page 
is  submitted. 

It  is  compiled  from  a  large  number  of  tests;  the  maximum  and  minimum  values 
are  given.  All  of  the  test  specimens  had  a  sectional  area  of  i. 575  by  1.575  square  inches. 
The  transverse  specimens  were  39.37  inches  between  supports,  and  the  compressive- 

test  specimens  were  12.60  inches  long.     The  modulus  of  rupture  is  calculated  from 

,    pi 
the  formula  R  =  -      —  • 

2    bd2 

P  =  load  in  pounds  at  the  middle. 
/  =  length  in  inches. 
b  =  breadth  in  inches. 
d  =  depth  in  inches. 


HEADRACE. 


53 


TABLE    I.  —  PROPERTIES    OF    TIMBER. 


Description. 

Weight 
per  cubic 
foot  in 
pounds. 

Weight 
per  foot 
B.M.  in 
pounds, 
average. 

Tensile 
strength  per 
square  inch, 
in  pounds. 

Crushing 
strength  per 
square  inch, 
in  pounds. 

Relative 
strength  for 
cross  breaking 
white  pine  = 
100. 

Shearing 
strength 
with  the 
grain, 
pounds  per 
sq.  in. 

Pressure 
in  pounds 
per  square 
inch  to 
indent 
0.05*. 

Ash  

43-55  -8 
43-53-4 
50-56.8 

4.1 
3-9 
4-5 

11,000—17,207 
11,500-18,000 
10,300-11,400 

4400-9363 
5800-9363 
5600-6000 

130-180 
100-144 

55-63 
130 
96-123 
96 

888-95 
132-227 

I22-22O 
130-177 

I55-I89 

TOO 
98-170 

86-110 

458-700 

1800-1850 

Beech  

Cedar  

Cherry  

Chestnut  

33 
34-36-  7 

2-75 

2-9 

10,500 
13,400-13,489 
8700 
20,500-24,800 
10,500-10,584 
10,253-19,500 

535°-56°° 
6831-10,331 

57°° 
911-5-11,700 
'8150 
4684-9509 
6850 
5000-5650 
5400-9500 
5050-7850 

Elm  

Hemlock  

Locust  

44 
49 
45-45-5 
7° 
3° 
28-8-33 

3-7 
4-i 
4-i 
5-8 

2-5 
2.6 

Maple  

367-647 
752-966 

1700-1900 
23°°-355° 

Oak,  white 

Oak,  live  

Pine,  white  

10,000-12,000 
12,600-19,200 
10,000-19,500 

225-423 
296-415 
253-374 

875-1160 
1900 
875-1025 

Pine,  yellow  

Spruce  

TABLE    II. —  TESTS    OF    AMERICAN    WOODS. 


Name  of  Wood. 

Transverse  tests, 
modulus  of 
rupture. 

Compression  parallel 
to  grain,  pounds 
per  square  inch. 

Max. 

Min. 

Max. 

Min. 

Yellow  poplar,  white  wood    

6,55° 

6,720 
8,610 

12,200 
8,310 

5,95° 
10,220 
8,250 
14,870 
7,010 
9,760 
7,900 
5,95° 
13.85° 
6,310 

5.64° 
5,610 
3,78° 
9,220 
9,900 
7,59° 

8,220 

10,080 

",756 
ii,53° 
13.45° 
2i,73° 
16,800 
15,800 
i3,952 
i5,°7° 
20,710 
18,360 

18,37° 
18,420 
12,870 
18,840 

9,53° 
15,100 

",53° 
10,980 
21,060 
11,650 
14,680 
17,920 
16,770 

4,15° 
3,810 
6,O  I  O 

8,33° 
5,83° 
4,520 
6,980 
4,960 

7,65° 
5,8io 
4,960 

4,54° 
3,680 

5,77° 
2,660 
4,400 

3,75° 
2,580 
4,010 
4,i5° 
4,5°° 
4,880 
6,810 

5,79° 
6,480 

7,5°° 
11,940 
9,120 
8,830 
8,790 
8,040 
10,280 
9,070 
8,970 

8,55° 
6,650 
7,840 
5,810 
7,040 
5,600 
4,680 
10,600 

5>3°° 
7,420 
9,800 
10,700 

\Vhite  wood,  basswood  .      .                                     «j__  . 

Red  maple  .                           .... 

Locust  

Wild  cherry  

White  ash  

Slippery  elm.    .            .        .            .        .    .        

White  elm  .                                                 .....            

Shellbark  hickory  

White  oak  

Red  oak  

Black  oak  

Chestnut  .....    .    .        

Beech  

White  cedar                         ...                                                   

Red  cedar  

White  pine  

Spruce  pine  

Long-leaved  pine,  southern  pine  

White  spruce  

Hemlock  .  .    .        

Red  fir,  yellow  fir  

Tamarack  

54 


HYDROELECTRIC    DEVELOPMENTS    AND    ENGINEERING. 


In  connection  with  wooden  sluice  gates,  particularly  with  less  expensive  or  tem- 
porary installations,  wooden  guides  are  sometimes  used.  Tables  I  and  II,  giving  the 
properties  of  timber  and  tests  of  woods,  may  be  used  in  connection  with  same. 

Wooden  sluice  gates,  as  they  are  usually  of  small  size,  may  be  operated  by  hand. 
Where  a  series  of  small  gates  are  opened  simultaneously,  they  may  be  operated  by  a 
single  motor.  Such  a  device  is  seen  in  Fig.  n.1  It  will  be  noticed  that  two  wooden 
sluice  gates,  side  by  side,  may  be  operated  separately,  by  hand  or  by  a  motor;  when 
desired,  both  gates  may  be  operated  simultaneously  by  a  motor;  friction  clutches  are 
located  on  both  sides  of  the  latter. 

Iron  Sluice  Gates.  Large  head  gates  are  usually  made  of  structural  steel,  and  on 
account  of  their  heavy  weight,  are  counterweighted.  Provision  must  be  made,  so 


FIG.  12. — Application  of  Drum  Gate,  Chevres  Plant,  France. 

that  they  may  be  operated  by  hand,  in  addition  to  the  regular  motor  operation  of 
same.  Low  head  plants  usually  employ  several  large-sized  gates;  they  must  be 
located  side  by  side,  and  interconnected  by  an  operating  bridge.  Where  the  turbine 
is  placed  in  an  open  chamber,  the  water  to  the  chamber  is  controlled  by  a  separate 
gate.  The  type  of  gate  varies  greatly  with  the  setting  of  the  turbine.  This  may  be 
done  by  a  vertically  operated  sluice,  drum  or  cylindrical  gate.  Sluice  gates  are  the 
most  common,  and  are  frequently  made  of  structural  steel,  provided  with  an  auxiliary 
gate  to  facilitate  operation;  large  gates  usually  are  operated  by  a  motor  or  hoist. 

1  Gelpke,  Turbinen  und  Turbinenanlagen. 


HEADRACE. 


55 


Where  quick  action  is  necessary,  they  are  operated  by  air  or  hydraulic  pressure.  A 
gate  of  the  latter  type  has  been  installed  in  the  Beznau  plant,  Switzerland.  They 
are  21.6  feet  wide  and  10.5  feet  high,  and  provided  with  rollers,  as  they  have  to  with- 
stand a  pressure  of  18.7  tons.  The  lifting  or  lowering  of  these  gates  is  accomplished 
by  oil  pressure,  supplied  by  the  same  pumps  furnishing  oil  to  the  step-bearings.  As 
the  sluice  gates  are  in  the  open  air,  the  cylinders  are  jacketed  to  protect  them  from 
frost.  To  protect  the  steel  piston  rod  from  rust,  it  is  fitted  with  a  brass  sleeve. 

Drum  gates  are  made  to  swing  either  vertically  or  horizontally.  A  type  of  the 
latter  has  been  installed  in  a  plant  at  Rheinfelden,  which  has  been  in  operation  for 
many  years.  To  the  writer's  knowledge,  it  has  never  been  duplicated.  A  more 


FIG.  13. — Detail  of  Drum  Gate. 

favored  one  is  the  vertical  swinging  type.  They  have  been  installed  at  Chevres, 
France,  and  in  many  other  plants.  As  the  water  presses  against  the  drum  (the  gate 
being  located  in  the  turbine  chamber;  see  Fig.  12),  care  must  be  taken  to  keep  it  tight, 
because  the  water  is  pressing  it  away  from  the  seat.  This  may  be  accomplished  by 
a  rope  or  steel  cable  on  top  of  the  gate  as  seen  in  Fig.  13,  and  on  the  bottom  by  wooden 


56  HYDROELECTRIC    DEVELOPMENTS   AND   ENGINEERING. 

blocks.  For  operating  the  gate,  a  chain  is  fastened  on  the  bottom  of  the  drum  and 
guided  by  sheaves.  It  may  be  raised  by  a  separate  hoist,  or  by  the  overhead  crane 
in  the  generating  room. 

The  application  of  a  cylindrical  gate  is  seen  in  Fig.  14.  The  whole  gate  consists 
of  a  cylinder  with  vertical  slots,  which  are  covered  and  uncovered,  by  moving  a  disk 
up  and  down  by  means  of  a  windlass. 

COLLECTING    BASIN. 

Scheme.  The  junction  between  the  headrace  and  the  penstock  must  be  made  by 
a  collecting  basin,  provided  it  is  not  a  pressure  tunnel.  This  collecting  basin  should 
be  large  enough  to  overcome  slight  fluctuations.  To  increase  the  capacity  of  such 


FIG.  14. — Application  of  Cylinder  Gate,  Lyon  Plant,  France. 

a  basin,  the  area  of  the  headrace  near  the  basin  may  be  enlarged  for  a  certain  length. 
This  may  be  well  adopted  if  the  headrace  is  a  tunnel.  Under  ordinary  conditions 
such  a  collecting  basin  is  large  enough  when  the  velocity  is  only  one  foot  per  second. 
This  velocity  is  sufficient  to  allow  all  heavy  foreign  material  to  settle,  thus  preventing 
it  from  entering  the  penstock.  In  most  cases,  the  entrance  to  the  penstock  must 


HEADRACE.  57 

be  protected  with  a  fine  screen,  to  prevent  foreign  material  from  entering  the  same. 
The  screens  are  preferably  placed  on  the  skew,  so  that  the  water  will  push  the  foreign 
material  to  the  gate  of  the  sandtrap. 

Sandtraps.  A  sandtrap  is  nothing  more  than  a  recess  in  the  bottom  of  the  collecting 
basin  or  headrace.  The  approach  to  the  sandtrap  must  be  gradual,  so  as  to  decrease 
the  velocity  of  the  water,  and  facilitate  the  settling  of  sand  and  gravel.  At  the 
deepest  point,  the  trap  is  about  two  or  three  feet  deep.  The  sandtrap  must  run  on  a 
skew,  so  that  the  foreign  material  will  roll  to  the  gate  at  the  end.  In  many  instances, 
there  is  no  gate,  only  an  opening,  and  the  sand  and  gravel  discharge  all  the  time  into 
the  spillway. 

Spillways.  The  collecting  basin  must  be  provided  with  a  spillway,  so  that  in  case 
the  water  to  the  penstock  is  cut  off,  and  the  water  in  the  headrace  is  not  cut  off,  no 
damage  is  done  to  the  collecting  basin  or  penstock  run.  The  spillway  is  usually 
nothing  more  than  a  partition  wall  in  the  collecting  basin  with  a  lower  elevation,  so 
that  the  surface  water  can  overflow.  The  spillway  must  be  provided  with  a  sluice 
gate,  so  that  the  collecting  basin  and  headrace  may  be  emptied  through  same.  To 
provide  for  protection  against  floating  material,  particularly  ice,  a  sluice  gate  to  be 
lowered  is  installed,  contrary  to  the  one  which  is  raised.  These  two  gates  may 
be  combined  into  one,  as  will  be  seen  under  Sluice  Gates. 

The  discharge  of  the  spillway  is  best  done  in  cascades  when  the  collecting  basin 
is  on  a  steep  mountain  slope,  and  discharged  either  into  a  river,  or  into  the  tailrace 
of  the  plant.  The  cascades  break  the  fall  of  the  water. 

Attention  is  here  called  to  the  spillway  of  the  Ontario  Power  Company,  Niagara 
Falls.  The  water  is  forced  over  an  adjustable  weir  and  discharged  into  a  vertical, 
helical  shaft,  which  opens  into  the  gorge  below  the  falls.  The  helical  course  was 
chosen  to  prevent  ice  formation. 

Gate  Valves.  All  penstocks  must  be  provided  with  cut-off  valves  at  the  collecting 
basin.  They  are  usually  of  the  gate  valve  type;  in  very  rare  instances  butterfly  valves 
have  been  used.  The  gate  valves,  also  classed  as  sluice  gates,  are  usually  of  simple 
form;  the  head  presses  the  disk  against  the  seat  and  keeps  it  tight.  They  are  usually 
made  of  cast  iron,  and  have  babbit  or  bronze  seats ( so  as  to  keep  them  from  rusting. 
When  large  valves  are  used,  by-pass  provision  should  be  made,  so  as  to  properly  fill 
the  penstocks  before  the  main  valve  is  opened.  The  valves  may  be  either  hand  or 
motor  operated;  they  are  sometimes  of  the  remote  control  type,  so  that  they  can  be 
operated  from  the  power  house. 

To  protect  the  operating  mechanism  of  the  gate  valves,  and  other  devices  connected 
to  the  inlet  of  the  penstock,  a  housing  should  be  provided.  In  medium  head  plants, 
screens  and  gates  may  be  of  such  size  that  they  are  difficult  to  handle  by  hand,  in 
which  case  a  hand-operated  traveling  crane  must  be  used. 


58  HYDROELECTRIC    DEVELOPMENTS   AND   ENGINEERING. 

BIBLIOGRAPHY. 

HYDRAULICS  AND  HYDRAULIC  MOTORS.     P.  J.  Weisbach.     Translated  by  A.  Jay  Dubois.     1891. 

John  Wiley  &  Sons.     New  York. 

A  TREATISE  ON  HYDRAULICS.     Henry  T.  Bovey.     1901.     John  Wiley  &  Sons.     New  York. 
TREATISE  ON  HYDRAULICS.     Mansfield  Merriman.     1903.     John  Wiley  &  Sons.     New  York. 
HYDRAULICS.     L.  M.  Hoskins.     1907.     Henry  Holt  &  Co.     New  York. 

RIVER  DISCHARGE.     J.  C.  Hoyt  and  N.  C.  Grover.     1907.     John  Wiley  &  Sons.     New  York. 
ICE  TROUBLES  IN  HYDRAULIC  POWER  WORKS  AND  METHODS  OF  OVERCOMING  THEM.   John  Murphy, 

Consulting  Engineer.     May  i,  1908. 

THE  FLOW  OF  WATER  OVER  DAMS  AND  SPILLWAYS.    Engineering  Record,  June  2,  1900. 
FLOW  OF  WATER  OVER  ROUNDED  CREST.    N.  Werenskiold.    Engineering  News,  Jan.  31,  1895. 
THE  FLOW  OF  WATER  OVER  DAMS.     Geo.  M.  Rafter.    Proc.  A.S.C.  E.,  March,  1900. 
EXPERIMENTS    ON   THE    MEASUREMENT   OF  WATER   OVER   WEIRS.    A.   E.   Victor    Dery.      Proc. 

I.  C.  E.,  vol.  114,  p.  333.     1893. 
EXPERIMENTS  ON  THE  FLOW  OF  WATER  THROUGH  LARGE  GATES  AND  OVER  A  WIDE  CREST.     Chas. 

E.  Kaberstroh.     Journal  Association  Engineering  Societies,  January,  1890. 
THE  ESTIMATION  OF  DAMAGES  TO  POWER  PLANTS  FROM  BACK  WATER.    Engineering  Record,  April  26, 

1902. 
INSTRUCTIONS  FOR  INSTALLING  WEIRS,  MEASURING  FLUMES  AND  WATER  REGISTERS.    Johnson. 

Engineering  News,  Aug.  29,  1901. 
NEW  FORMULA  FOR  CALCULATING  THE  FLOW  OF  WATER  IN  PIPES  AND  CHANNELS.    W.  E.  Foss. 

Journal  Association  Engineering  Societies,  vol.  13,  p.  295.     1894. 
MEASUREMENT  AND  DIVISION  OF  WATER.    L.  G.  Carpenter.     Bulletin  27,  Colorado  Agricultural 

Experiment  Station,  Fort  Collins,  Colorado.    1894. 
DISCHARGE  MEASUREMENTS  OF  STREAMS.    F.  H.  Newell.    Proceedings  Engineering  Club,  Philadelphia, 

vol.  12,  No.  2,  p.  125.     1895. 
COEFFICIENTS  IN  HYDRAULIC  FORMULAS.    W.  J.  Keating.    Journal  Western  Society  Engineering, 

vol.  i,  p.  190.     1896. 
EXPERIMENTAL  DATA  FOR  FLOW  OVER  BROAD  CREST  DAM.    F.  T.  Johnson  and  E.  L.  Cooley.    Journal 

Western  Society  Engineering,  vol.  i,  p.  30.     1896. 

STEAM  GAUGINGS.     Clarence  T.  Johnson.     Proceedings  Purdue  Society  Civil  Engineers.     1897. 
METHODS  OF  STEAM  MEASUREMENT.    Water  Supply  and  Irrigation  Paper,  No.  56.     1901. 
ACCURACY  OF  STEAM  MEASUREMENT.    E.  C.  Murphy.     Water  Supply  and  Irrigation  Paper,  No.  64. 

1901. 

THE  LAWS  OF  RIVER  FLOW.     C.  H.  Tutton.    Journal  Association  Engineering  Societies,  January,  1902. 
METHODS  OF  MEASURING  THE  FLOW  OF  STREAMS.     John  C.  Hoyt.    Engineering  News,  Jan.  14, 

1904. 
A  METHOD  OF  COMPUTING  FLOOD  DISCHARGE  AND  CROSS  SECTION  AREA  OF  STREAMS.    E.  C.  Murphy. 

Engineering  News,  April  6,  1905. 


CHAPTER   IV. 
PENSTOCKS. 

STEEL    PENSTOCKS. 

Penstock  Run.  Penstocks  must  be  laid  in  the  shortest  course  to  the  power  house, 
and  in  such  a  way  as  to  avoid  sharp  turns.  This  may  be  done  by  running  the 
penstocks  through  tunnels  or  trenches,  or  crossing  valleys  on  trestles  or  piers. 
Conforming  to  modern  practice,  instead  of  one  large  penstock,  several  small  ones 
are  installed.  They  should  be  arranged  side  by  side,  and  the  bed  selected  for  same 
should  be  as  even  as  possible.  If  the  natural  ground  cannot  carry  the  penstocks,  it 
must  be  reinforced  to  avoid  any  possibility  of  a  semi-landslide,  which  in  some  cases 
have  put  plants  out  of  commission. 

Where  a  number  of  such  penstocks  are  installed,  it  is  well  to  build  as  part  of  the 
penstock  bed,  a  permanent  cable  road,  by  which  means  sections  of  the  penstocks  are 
hoisted  to  place,  as  well  as  to  facilitate  the  building  of  the  penstock  run;  later  on, 
the  cableway  is  used  for  inspection  and  repair  purposes. 

Where  multiple  penstocks  are  laid,  they  must  be  interconnected,  preferably  at 
the  power  house,  and  properly  equipped  with  valves,  so  that  in  case  of  emergency, 
the  water  of  one  penstock  may  feed  other  turbines. 

Size  of  Penstocks.  The  size  of  the  penstocks  depends  upon  the  amount  of  water 
to  be  carried  and  head  available.  Other  conditions  remaining  the  same,  the  velocity 
of  water  in  a  penstock  under  a  high  head  must  be  greater  than  under  a  low  head. 
However,  plants  have  been  installed,  where  the  velocity  in  the  penstocks  under  low 
and  high  heads  is  practically  the  same.  For  instance,  with  the  horizontal  section  of 
the  i8-foot  penstock  of  the  Ontario  Power  Company,  Niagara  Falls,  under  a  head  of 
about  20  feet,  the  velocity  is  15  feet  per  second;  the  velocity  in  the  3O-inch  penstock 
of  the  Necaxa  plant,  under  a  head  of  1300  feet,  is  15  feet  under  normal  full  load, 
while  under  extremely  high  load,  it  is  18  feet  per  second. 

As  stated,  the  smaller  the  penstocks,  the  higher  the  velocity;  in  some  plants  with 
penstocks  i  to  2  feet  in  diameter,  the  water  has  a  velocity  of  20  to  30  feet  per  second. 
In  most  high  head  plants  running  under  a  head  of  1000  feet  and  higher,  and  penstocks 
2  to  3  feet  in  diameter,  the  velocity  chosen  is  between  10  to  16  feet  per  second.  The 
velocity  of  the  water  in  the  penstock  depends  greatly  on  the  velocity  in  the  turbine 
gates,  or,  in  other  words,  the  speed  for  which  the  water  wheel  has  been  designed. 
Therefore,  the  lower  sections  or  branches-must  be  designed  to  suit  conditions.  The 
main  penstock  must  not  have  any  sudden  enlargements  of  diameter.  The  use  of  a 
drum  at  the  end  of  a  penstock,  from  which  branches  run  to  several  turbines,  must 
be  avoided,  because  of  the  sudden  change  of  speed  in  the  water. 

59 


•>?.-    i  At 

60  HYDROELECTRIC    DEVELOPMENTS    AND   ENGINEERING. 

TABLE   I.  — AREA  OF  CIRCLES. 


1 
i 

•79 
1.77 

18 

i 

254.47 
268.80 

35 

J 

962.  ii 
989.80 

52 

2123.72 
2164.  76 

69 

3739-29 

3793-68 

86 

\ 

5808.82 
5876.56 

2 

1 

3-14 
4.90 

19 

i 

283-53 
298.65 

36 

1017.87 
1046.34 

53 

1 

2206.  19 
2248.  01 

70 

3848.46 
3903-63 

87 

5944-69 

6013.  22 

3 

i 

7.06 
9.  62 

20 

314.16 
330.06 

37 

1175.21 
1104.46 

54 

2290.  23 
2332-83 

71 

3958.20 
4015.16 

88 

i 

6082.  14 
6I5I-45 

4 

12.56 
15.90 

21 

346.36 
363-05 

38 

1134.11 
i  i  64  .  i  6 

55 

\ 

2375-83 
2419.23 

72 

407I-51 
4128.  26 

89 

6221  15 
6291.  25 

6 

i 

19.63 
23-75 

22 

380.13 
397-61 

39 

1194.59 
1225.42 

56 

2463.01 

2507.19 

73 

4185.40 
4242.93 

90 

6361  74 
6432.  62 

6 

28.27 
33.18 

23 

i 

415.48 
433-74 

40 

i 

1256.64 
1288.25 

57 

2551-76 
2596.73 

74 

4300.85 
4359.I7 

91 

6503.90 
6575-56 

7 

38.48 
44-17 

24 

452.39 
471-44 

41 

1320.  25 
1352-65 

58 

i 

2642.09 
2687.84 

75 

4417-87 
4476.98 

92 

6647  65 
6720  08 

8 

50.26 
S6-74 

25 

i 

490.88 
510.71 

42 

1385-45 
1418.63 

59 

\ 

2733-98 
2780.51 

76 

\ 

4536.47 
4596-36 

93 

6792.92 
6866.  i  6 

9 

i 

63.61 

70.88 

26 

530.93 

551-55 

43 

1452.20 
1486.  17 

60 

2827.44 
2874.76 

77 

4656.  64 
4117.  31 

94 

\ 

6939-79 
7013.82 

10 

i 

78.54 
86.59 

27 

593-95 

44 

1520.53 
I555.29 

61 

2922.47 
2970.58 

78 

4778.37 
4839-83 

95 

i 

7088.23 
7163.04 

11 

95.03 
103.87 

28 

6i5-75 
637.94 

45 

i 

1590.43 
1625.97 

62 

3019.08 
3067.97 

79 

4901.  68 
4963.92 

96 

i 

7238.25 
73I3-84 

12 

113.10 

122.  72 

29 

660.52 
683.49 

46 

i 

1661.91 
1698.23 

63 

3166.93 

80 

5026.56 
5089.59 

97 

7389-83 

7466.  21 

13 

I43.I3 

30 

706.  86 
730.62 

47 

1734-95 
1772.06 

64 

i 

3217.00 
3267.46 

81 

5216.82 

98 

7542.98 
7620.  15 

14 

153-94 
165-13 

31 

i 

754-76 
779-31 

48 

1809.56 
1847.46 

65 

3318.31 
3369-56 

82 

5281.03 

99 

i 

7697.71 
7775.66 

15 
16 

176.72 
188.69 

2OI.o6 

32 
33 

804.25 
855.  30 

49 
50 

1924.43 
1067.  so 

66 
67 

3421.20 
3473-24 

3525.  66 

83 
84 

5410.62 
5476.01 

554I-78 

100 

7854.00 

217.  87 

881.41 

i 

i  y^  j  o 

2OO2.  Q7 

708.48 

§ 

C6O7.  (K 

17 

O        J 

226.  98 

34 

OO7.  Q2 

• 
51 

71 

2O42.  83 

68 

OJf         ~ 

3631  .  69 

85 

*J            /       7  J 

1:674..  <!I 

24O.  C7 

§ 

yw  I       y.6. 
934.  82 

2083.08 

\ 

7.68?.  20 

§ 

J     1  ^    O 

5741.  47 

T       •   JO 

\J          J          V 

It  is  frequently  desirable  to  know  what  number  of  one-sized  pipes  will  be  equal 
in  capacity  to  another  pipe,  for  a  given  delivery  of  water.  At  the  same  velocity  of 
flow,  two  pipes  deliver  as  the  squares  of  their  internal  diameters,  but  the  same  head 
will  not  produce  the  same  velocity  in  pipes  of  different  sizes  or  lengths,  the  difference 
being  usually  stated  to  vary  as  the  square  root  of  the  fifth  power  of  the  diameter. 

The  friction  of  water  within  itself  is  very  slight,  and  therefore  the  main  resistance 
to  flow  is  the  friction  upon  the  sides  of  the  conduit.  This  extends  to  a  limited  dis- 
tance, and  is,  of  course,  greater  in  proportion  to  the  contents  of  a  small  pipe  than  of 
a  large  one.  It  may  be  approximated  in  a  given  pipe,  by  a  constant  multiplied  by 
the  diameter,  or  the  ratio  of  flow  found  by  dividing  some  power  of  the  diameter 


A.E.&M.E 


PENSTOCKS. 

by  the  diameter  increased  by  a  constant.     Careful  comparison  of  a  lar 
experiments,   by   different   investigators,   has  developed   the   following,   as   a 
approximation  to  the  relative  flow  in  pipes  of  different  sizes  under  similar  conditions: 

w      t/Z"?H  d* 

W  oo  V  —. : ,   or. 


61 
6F  CA 


W  being  the  weight  of  fluid  delivered  in  a  given  time,  and  d  being  the  internal 
diameter  in  inches. 

Friction.    The  laws  governing  the  theoretical  flow  of  water  in  long  penstocks  are 
derived  chiefly  from  the  formula: 

v  =  \/2  gh. 

The  losses  due  to  friction  depend  upon  the  length  and  diameter  of  the  pipes,  also  the 
conditions  of  the  inside  of  same,  whether  rusty,  full  of  silt,  dents  in  the  pipe,  etc.  In 
brief,  the  laws  may  be  stated  as  follows: 

1.  For  equal  velocities,  the  friction  loss  is  proportional  to  the  length  of  penstock. 

2.  Friction  increases  very  nearly  as  the  square  of  the  velocity. 

3.  For  equal  lengths  of  pipe,  the  friction  decreases  with  the  diameter. 

4.  The  rougher  the  interior  surface,  the  greater  the  friction. 

Loss  of  Head.    The  loss  of  head  is  chiefly  due  to  the  friction  of  water  in  the  pen- 
stock, and  may  be  calculated  according  to  Weisbach  as  follows: 

,        /  ,   .oi7i6\   /     v~ 

h  =     .0144  +--Jr-J  -      -• 
\  \/v    I  d    2  g 

h  =  loss  of  head. 
I  =  length  of  penstock  in  feet. 
d  —  diameter  of  penstock  in  feet. 
v  —  velocity  in  feet  per  second. 

Another  formula  deduced  by  Wm.  Cox,  is  as  follows: 


F  =  friction  head. 

L  =  length  of  pipe  in  feet. 

D  -—  diameter  of  pipe  in  inches. 

V  =  velocity  in  feet  per  second. 

Table  II  has  been  abstracted  from  tables  given  by  the  Pelton  Water  Wheel  Com- 
pany. It  gives  the  loss  of  head  by  friction  for  each  100  feet  of  penstock  for  different 
diameters  under  different  discharges  in  cubic  feet  at  velocities  from  2  to  7  feet  per 
second.  The  Cox  formula  gives  practically  the  same  result. 

Table  III  gives  the  capacity  and  friction  head  for  velocities,  varying  from  8  to 
15  feet  per  second.  It  must  be  noticed  that  the  discharge  is  in  gallons  per  minute. 
One  U.  S.  gallon  =  0.133  cubic  foot. 


62 


HYDROELECTRIC    DEVELOPMENTS    AND   ENGINEERING. 


TABLE    II.— LOSS    OF   HEAD    BY   FRICTION    IN   PENSTOCKS. 

Inside  diameter  of  pipe  in  inches. 


12 

13 

14 

15 

16 

18 

Vel. 
in 
feet 

I.oss 
of 
head 

Cubic 
feet 

Loss 
of 
head 

Cubic 
feet 

Loss 
of 
head 

Cubic 
feet 

Loss 
of 
head 

Cubic 
feet 

Loss 
of 
head 

Cubic 
feet 

Loss 
of 
head 

Cubic 
feet 

per 

per 

per 

per 

per 

per 

sec. 

feet. 

mm. 

feet. 

mm. 

feet. 

mm. 

feet. 

mm. 

feet. 

mm. 

feet. 

mm. 

2.0 

.198 

94 

•183 

110 

.  169 

128 

,IS8 

147 

.147 

167 

.132 

212 

3-° 

.407 

141 

•375 

1  66 

•349 

192 

•325 

221 

.306 

251 

.271 

3i8 

4.0 

.685 

1  88 

.632 

221 

•SB? 

256 

.548 

294 

•513 

335 

•456 

424 

5-o 

1.03 

235 

•949 

276 

.881 

321 

.822 

368 

.770 

419 

.685 

53° 

6.0 

1-43 

283 

I-325 

332 

I.  229 

3«5 

1.148 

442 

1.076 

502 

•957 

636 

7.0 

1.91 

33° 

i-75 

3«7 

1.630 

449 

1.520 

515 

1.430 

586 

1.270 

742 

20 

22 

24 

23 

28 

30 

2.O 

.119 

262 

.108 

316 

.098 

377 

.091 

442 

.084 

5i3 

.079 

589 

3-° 

•245 

393 

.  222 

475 

.  204 

S6S 

.188 

663 

.174 

770 

.163 

883 

4.0 

.410 

523 

•373 

633 

•342 

754 

•3i5 

885 

•293 

1026 

•  273 

1178 

5-o 

.617 

654 

.561 

792 

•5i3 

942 

•  474 

1106 

.440 

1283 

.411 

1472 

6.0 

.861 

7«S 

.782 

95° 

.717 

1131 

.662 

1327 

.615 

1539 

•574 

1767 

7.0 

1-143 

916 

1.040 

1109 

•953 

13*9 

.879 

1548 

.817 

1796 

.762 

2061 

33 

36 

39 

42 

45 

48 

2.0 

•073 

712 

.066 

848 

.061 

995 

•057 

H55 

•°53 

1325 

.050 

1508 

3-o 

.148 

1070 

•135 

1273 

•125 

1442 

.117 

173° 

.  109 

1987 

.  IO2 

2260 

4.0 

.248 

1425 

.228 

1697 

.  2IO 

1990 

•195 

2310 

.182 

2650 

.171 

3016 

S-o 

•374 

1780 

•342 

2121 

•3l6 

2490 

.294 

2885 

•273 

331° 

.256 

377° 

6.0 

.520 

2140 

•479 

2545 

.441 

2986 

.408 

346i 

.382 

3970 

•35* 

4524 

7.0 

•693 

2495 

.636 

2968 

.586 

3484 

•545 

4030 

•5°9 

4638 

.476 

5277 

PENSTOCKS. 


TABLE  III.  — CAPACITY  IN  GALLONS  PER  MINUTE  DISCHARGED  AT  VELOCITIES  IN 
FEET  PER  SECOND,  FROM  8  TO  15;  ALSO  FRICTION  HEAD  IN  FEET  PER  100  FEET 
LENGTH  OF  PIPE. 


Dia. 
Pipe. 

i-inch. 

2-inch. 

3  -inch. 

4-inch. 

5  -inch. 

6-inch. 

Dia. 
Pipe. 

| 

"o 

.0 

'o 

jj 

| 

_g 

£ 

d 

| 

d 

f±> 

| 

| 

o 

a 

tj 

a 

•5 

a 

o 

a 

a 

'•§ 

1 

ft 

•8 

a 

o 

i 

V 

£ 

a 
tj 

£ 

c3 

£ 

O 

£ 

OS 
O 

£ 

6 

£ 

1 

8 

19.58 

24-5 

78.32 

12.  2 

176.24 

8.16 

314.12 

6.  12 

489.68 

4-90 

705.64 

4.0? 

8 

Si 

20.  80 

27.4 

83-23 

13-7 

187.25 

9.  15 

333-75 

6.86 

520.  61 

5-49 

749.01 

4-57 

8* 

9 

22.03 

30.5 

88.11 

15.2 

198.  27 

10.  I 

352-26 

7.64 

550-89 

6.  ii 

793-72 

5-o? 

9 

9i 

23-25 

33-8 

93-0° 

16.9 

209.  24 

II.  2 

371.90 

8.46 

581.25 

6-77 

837.08 

5.61 

IO 

24.48 

37-3 

97.90 

18.6 

220.  30 

12.4 

391.40 

9-33 

612.  10 

7.46 

88i.8c 

6.  21 

IO 

ioj 

25.70 

40.9 

102.80 

20.  4 

231-3! 

13.6 

411.05 

IO.  2 

642.43 

8.19 

925.20 

6.82 

105 

ii 

26.  92 

44-7 

107.  69 

22.3 

242.33 

14.9 

430-54 

II.  I 

673-31 

8-95 

969.88 

7-45 

II 

nj 

28.15 

48.7 

112.58 

24-3 

253-34 

16.  2 

450.  20 

12.  I 

703.62 

9-74 

1013.3 

8.  ii 

Hi 

12 

29-37 

52.8 

117.48 

26.4 

264.36 

17.6 

470.68 

13.2 

734.52 

10.5 

I057-9 

8.8c 

12 

13 

31.82 

61.5 

127.27 

30.7 

286.39 

20.5 

509.82 

15-3 

795-73 

12.3 

1145.0 

10.  2 

13 

14 

34.27 

71.0 

137.06 

35-5 

308.42 

23-7 

548.96 

17.7 

856.94 

14.2 

1233.1 

ii.  8 

14 

15 

.36.72 

81.0 

146.85 

40.5 

330-45 

2.  70 

587.10 

20.3 

918.15 

16.  2 

1321.2 

13-5 

15 

Dia 

7-inch. 

8-  inch. 

i  o-  inch. 

1  2-inch. 

i  s-inch. 

1  8-inch. 

Dia. 

Pipe. 

Pipe. 

^ 

£ 

d 

>, 

d 

£ 

d 

>, 

d 

>, 

d 

£ 

d 

£ 

.0 

_g 

_g 

1 

1 

ft 

I 

*j 

a 

'| 

m 

a 

_o 

a 

u 

I 

ft 

1 

<L> 

Q 

£ 

0 

£ 

a 
O 

£ 

£ 

6 

£ 

6 

u 

fc 

!> 

8 

(KQ.  44 

3-  49 

1253.  4 

3.06 

iot;8.  4 

2.  45 

2820.  i 

2.08 

8 

7j7       "^ 
IOI9.4 

3-92 

o 

3-43 

*  y  j~^  .  *f 
2080.8 

2.74 

2996.3 

2-33 

4688.  I 

1.82 

6741.9 

1.52 

9 

1079.4 

4-36 

1410.  i 

3.82 

2203.  2 

3-05 

3172.7 

2.  60 

4957-7 

2.04 

7138.1 

1.70 

9 

9* 

II39-4 

4-83 

1488.0 

4-23 

2325.6 

3-38 

3348.9 

2.88 

5232-1 

2.25 

7534-8 

1.88 

9i 

10 

H99-3 

5-33 

1566.8 

4.66 

2448.0 

3-73 

3525    2 

3-17 

2-5° 

7931-0 

2.07 

10 

loj 

1259-3 

5-84 

1645.8 

5-  22 

2570.8 

4.09 

370I.4 

3.48 

5783-4 

2-73 

8328.8 

2.27 

io| 

ii 

I3I9.2 

6-39 

1723-5 

5-59 

2692.8 

4-47 

3877.7 

3.80 

6058.  2 

2.98 

8724.9 

2.48 

ii 

nj 

1379.2 

6  95 

1801.5 

6.08 

2815.2 

4.87 

4053.8 

4.14 

6334.6 

3-25 

9121.7 

2.  70 

ni 

12 

1439-2 

7-54 

1880.2 

6  60 

2937.6 

5.28 

4230.2 

4-49 

6609  .  9 

3-52 

95I7.8 

2-93 

12 

13 

I559-I 

8.79 

2036  8 

7.90 

3182.4 

6.15 

4582.8 

5-23 

7  i  60  .  6 

4.  10 

10310. 

3-42 

13 

14 

1679.0 

10.  I 

2193-5 

8.87 

3427.2 

7.10 

4935-4 

6.03 

7711.4 

4.73 

11104. 

3-93 

14 

15 

1799.0 

ii.  6 

2350.2 

10.  I 

3672.0 

8.10 

5287.8 

6.89 

8262.1 

5-40 

11897. 

4-5° 

15 

Dia. 
Pipe 

20-inch. 

24-inch. 

30-  inch. 

36-inch. 

42-inch. 

48-inch. 

Dia. 
Pipe. 

£ 

J 

d 

£ 

d 

£ 

d 

>, 

d 

>, 

d 

£ 

d 

i 

•ti 

"o 

g 

'o 

.9 

o 

_g 

o 

.0 

'3 

_g 

•3 

•ti 

JD 

a 

0 

a 

0 

a 

a 

^o 

a 

ft 

tj 

a 

'o 

a 

o 

,0 

"3 

01 

O 

£ 

6 

£ 

d 
O 

£ 

a 
O 

£ 

6 

£ 

6 

£ 

£ 

81 

8323-^ 

i-37 

11985. 

1.14 

18725. 

•915 

26967. 

.760 

36704. 

•653 

47942. 

•571 

8* 

9 

88l2. 

i-53 

12690. 

1.27 

19827. 

I.  01 

28554. 

.847 

38863. 

.728 

50762. 

•  636 

9 

9* 

9302.  (. 

i.  69 

13395- 

1.40 

20928. 

I.  12 

30140. 

-938 

41022. 

.806 

53582. 

.694 

9$ 

10 

9792. 

1.87 

14100. 

i-55 

22030. 

1.24 

31726. 

1.03 

43181. 

.888 

56403. 

.778 

IO 

loj 

I028l. 

2.05 

14805. 

1.70 

23I3I- 

1.36 

33313- 

!-!3 

45340. 

•975 

59223- 

-851 

ioj 

II 

10771. 

2.  24 

15510- 

1.86 

1-49 

34899. 

1.16 

47499- 

i.  06 

62043. 

•93° 

ii 

II* 

11258. 

2-43 

16215. 

2.03 

25338^ 

i.  62 

36485. 

i-35 

49658. 

1.16 

64863. 

I.OO 

"I 

12 

II750. 

2.  64 

16920. 

2.  2O 

26436. 

i.  76 

38072. 

1.46 

51817. 

i.  26 

67683. 

I.  10 

12 

13 

12729. 

3.08 

18330. 

2.56 

28639. 

2.05 

41244. 

i.  70 

1.46 

73324- 

1.28 

13 

14 

13708. 

3-55 

19740. 

2-95 

30842. 

2-37 

44417- 

i-97 

60453- 

i.  69 

78964. 

1.48 

14 

15 

14688. 

4-05 

21150. 

3-37 

33045- 

2.  70 

47590. 

2.  24 

64771. 

i-93 

84604. 

1.69 

15 

64  HYDROELECTRIC    DEVELOPMENTS    AND    ENGINEERING. 

Strength.  In  calculating  the  thickness  of  the  penstock  shell,  the  following  formula 
may  be  used : 

t  =  -^. 
T 

t  =  thickness  of  shell  in  inches. 
P  =  pressure  in  pounds  per  square  inch. 
d  =  internal  diameter  in  inches. 
T  =  tensile  strength. 
s  =  factor  of  safety. 

Tensile  strength  of  mild  steel  may  be  taken  as  60,000  pounds  per  square  inch. 
Wrought  iron  50,000  pounds  per  square  inch. 

For  calculating  the  circumferential  pressure  in  a  penstock,  the  following  formula 

may  be  used: 

.       pr 

i  =  — •• 
t 

i  =  intensity  of  strain. 

p  =  pressure  head. 

r  =  radius  of  pipe. 

/  =  thickness  of  shell. 

For  stresses  in  riveted  pipes,  the  following  formula  may  serve: 

i  =  elk. 

i  =  intensity  of  strain. 

e  =  modulus  of  elasticity. 

t  =  change  of  temperature. 

k  =  coefficient  of  expansion. 

In  low  head  plants,  where  large-sized  penstocks  are  used,  the  plates  are  made 
heavier,  so  that  when  the  penstocks  are  emptied,  they  will  retain  their  form.  Another 
way  to  accomplish  the  same  result  is  to  reinforce  the  top  section. 

Construction.  Steel  penstocks  are  made  either  riveted  or  welded.  The  former 
is  made  up  of  sheet  steel  or  iron  plates,  which  are  rolled  in  the  shop  or  field.  The 
latter  is  resorted  to,  only  in  the  case  of  very  large  pipes,  in  order  to  save  freight  rates. 
Lap  joints  are  made  single,  double  or  triple  riveted  according  to  the  head  used. 
Under  high  heads  the  number  of  rivets  in  the  lower  sections  of  the  penstocks  increase; 
this  means  additional  friction  or  loss  of  head.  To  overcome  these  difficulties,  many 
plants  use  welded  pipes  in  such  places;  among  the  prominent  ones  on  the  American 
Continent  is  the  Necaxa  plant  in  Mexico.  Of  the  penstocks  installed  at  this  plant, 
there  are  6  thirty-inch  penstocks,  each  having  a  length  of  2460  feet.  The  lowest 
sections  are  subjected  to  a  static  head  of  1200  to  1300  feet.  They  are  seamless 
welded  pipes,  and  have  a  thickness  varying  from  0.4  to  0.95  of  an  inch,  and  were 
shipped  from  Germany  in  29.5-foot  lengths. 

A  system  of  welding  steel,  particularly  penstocks,  pipes,  etc.,  has  been  in  use  in 
Germany  for  a  number  of  years.  It  is  strange  to  note  that  American  firms  are  very 
slow  to  adopt  this  system;  because  of  this  a  large  number  of  penstocks,  amounting 
to  many  miles,  are  purchased  abroad  and  shipped  to  the  American  Continent. 


PENSTOCKS. 
TABLE  IV.  —  RIVETED  HYDRAULIC  PIPES. 


1 

II. 

O 

3  1 

CO 

Ii 

*j  d 

3 

CO 

c  « 
S  -o 

£ 

£ 

|l 

~s  <s 

|| 

1  » 

o* 

CO  f 

3 

'a 

*-i  2 

o 

«  to 

3 

"o  J3 

O  </]  Co 

c  •" 

co  a 

*o  <8 

°  w  M 

w  -S 

£  >> 

s  a 

0 

1  1 

S  p  M 

_co  g 

rt  "* 

>  0} 

[3 

SI 

|W  I 

"<*  ^ 

.s| 

c 

CO 

_o 

•3  £ 

c-  c 

•d  ^5 

11 

I 

^O 

" 

_>  $ 

•a  ~3 

cd  ^3 

•fl 

.5 
Q 

Pi 

W 

«  * 

'I 

5 

w 

E* 

3 

18 

•  O^ 

810 

2.25 

18 

12 

.  109 

295 

25-25 

4 

18 

•  O^ 

607 

3.00 

18 

II 

•  125 

337 

29.00 

4 

16 

.062 

760 

3-75 

18 

10 

.14 

378 

32-5° 

5 

18 

•°5 

485 

3-75 

18 

8 

.171 

460 

40.00 

5 

16 

.062 

605 

4-5° 

20 

16 

.062 

151 

16.00 

5 

14 

.078 

757 

5-75 

20 

14 

.078 

189 

19-75 

6 

18 

.05 

405 

4-25 

20 

12 

.  109 

265 

27.50 

6 

16 

.062 

505 

5-25 

20 

II 

.125 

3°4 

3!-5o 

6 

14 

.078 

630 

6.50 

2O 

10 

.14 

340 

35-oo 

7 

18 

.05 

346 

4-75 

2O 

8 

.171 

415 

45-5° 

7 

16 

.062 

433 

6.00 

22 

16 

.062 

138 

17-75 

7 

U 

.078 

540 

7-5° 

22 

14 

.078 

172 

22.00 

8 

16 

.062 

378 

7.00 

22 

12 

.  109 

240 

30-5° 

8 

14 

.078 

472 

8-75 

22 

II 

•  125 

276 

"34-50 

8 

12 

.  109 

660 

12.00 

22 

10 

.14 

309 

39.00 

9 

16 

.062 

336 

7-50 

22 

8 

.171 

376 

50.00 

9 

14 

.078 

420 

9-25 

24 

14 

.078 

158 

23-75 

9 

12 

.  109 

587 

12-75 

24 

12 

.  109 

220 

32.00 

10 

16 

.062 

3°7 

8-25 

24 

II 

•  125 

253 

37-50 

IO 

14 

.078 

378 

10.25 

24 

10 

.14 

283 

42.00 

IO 

12 

.  109 

530 

14.25 

24 

8 

.171 

346 

50.00 

10 

II 

•125 

607 

16.25 

24 

6 

.  20 

405 

59-oo 

10 

10 

.14 

680 

18.25 

26 

14 

.078 

145 

25-5° 

ii 

16 

.062 

275 

9.OO 

26 

12 

.  109 

203 

35-50 

ii 

14 

.078 

344 

11.00 

26 

II 

.125 

233 

39-5° 

ii 

12 

.  109 

480 

15-25 

26 

IO 

.14 

261 

44-25 

ii 

II 

•125 

553 

17-50 

26 

8 

.171 

319 

54-oo 

ii 

10 

.14 

617 

19-50 

26 

6 

.  20 

373 

64.00 

12 

16 

.062 

252 

IO.OO 

28 

14 

.078 

135 

27.25 

12 

14 

.078 

316 

12.  25 

28 

12 

.  109 

1  88 

38.00 

12 

12 

.  109 

442 

17.00 

28 

II 

•125 

216 

42.25 

12 

II 

•125 

506 

19.50 

28 

10 

.14 

242 

47-50 

12 

10 

.14 

567 

21.  75 

28 

8 

.171 

295 

58.00 

13 

16 

.062 

233 

10.  50 

28 

6 

.  20 

346 

69.00 

13 

14 

.078 

291 

13.00 

30 

12 

.  IO9 

176 

39-50 

13 

12 

.  109 

407 

18.  oo 

3° 

II 

•125 

202 

45-0° 

13 

II 

.125 

467 

20.50 

3° 

10 

•14 

226 

50-5° 

13 

10 

.14 

522 

23.00 

30 

8 

.171 

276 

61.  75 

14 

16 

.062 

216 

11.25 

30 

6 

.  2O 

323 

73-0° 

14 

14 

.078 

271 

14.00 

30 

1 

•25 

404 

90.00 

14 

12 

.  109 

378 

19.50 

36 

ii 

•125 

1  68 

54-oo 

14 

II 

•125 

433 

22.25 

36 

10 

.14 

189 

60.50 

14 

IO 

.14 

485 

25.00 

36 

A 

.l87 

252 

81.00 

15 

16 

.062 

202 

ii.  75 

36 

1 

•25 

337 

109.00 

15 

14 

.078 

252 

14-75 

36 

A 

.312 

420 

135-0° 

15 

12 

.  109 

352 

20.  50 

40 

10 

.14 

170 

67.50 

15 

II 

.125 

405 

23.  25 

40 

A 

.187 

226 

90.00 

15 

10 

-14 

453 

26.OO 

40 

i 

•25 

3°3 

I2O.OO 

16 

16 

.062 

190 

13.00 

40 

A 

.312 

378 

I5O.OO 

16 

14 

.078 

237 

16.00 

40 

| 

•375 

455 

iSo.OO 

16 

12 

.  109 

332 

22.25 

42 

IO 

162 

7I.OO 

16 

II 

•125 

379 

24.50 

42 

^ 

:ls7 

216 

94-5° 

16 

10 

-14 

425 

28.50 

42 

i 

•  25 

289 

I26.0O 

18 

16 

.062 

1  68 

14-75 

42 

A 

.312 

360 

158.00 

-18 

14 

.078 

2IO 

18.50 

42 

1 

•375 

435 

I9O.OO 

66 


HYDROELECTRIC    DEVELOPMENTS   AND    ENGINEERING. 


This  process  is  known  as  "autogenous  welding."  It  embraces  all  methods  of 
welding  in  which  the  parts  are  joined  in  a  homogeneous  manner,  the  joints  being 
made  by  the  intermingling  contacts  of  the  fibers  of  the  material  to  be  welded,  so  that 
the  finished  piece  is  one  of  uniform  quality  and  properties  throughout.  The  process 
is  carried  on  by  several  methods,  viz.,  the  oxy-acetylene,  the  purely  electrical,  and 
the  oxy-hydrogen  method.  The  latter  is  the  most  extensively  used,  and  has  been 
discussed  by  the  author  in  the  technical  press.1 

By  using  welded  penstocks,  it  will  be  readily  observed  that  additional  head  is 
obtained  because  of  the  absence  of  rivets. 

No  fixed  rules  can  be  laid  down  for  penstock  construction,  as  it  all  depends  upon 
the  nature  of  the  conditions  under  which  the  steel  penstock  is  to  be  constructed. 
To  give  an  example  of  a  prominent  steel  penstock  construction  on  the  American 
Continent,  that  of  the  Kern  River  Power  Plant2  of  California  is  cited.  It  has  many 
notable  features,  and,  contrary  to  the  customary  practice  on  mountain  slopes,  it  is 
run  through  tunnels.  The  steel  penstock  serves  as  a  lining  to  the  rock-cut  tunnel. 

The  penstock  consists  of  a  tunnel  approximately  1700  feet  long  driven  through 
the  mountains  on  an  incline  and  lined  with  steel,  varying  in  thickness  from  ^  to 
i£  inches.  This  tunnel  begins  at  the  bottom  of  the  forebay,  and  is  carried  down  at  an 
angle  of  approximately  45  degrees,  and,  turning  into  the  horizontal  section,  emerges 
at  the  lower  end  on  a  level  with  the  floor  of  the  power  station.  There  are  three 
vertical  curves  in  the  tunnel.  The  upper  one  forms  an  angle  of  7  degrees,  260  feet 
from  the  forebay  floor,  and  turns  the  pipe  from  a  grade  of  130.32  per  cent  to  a  grade 
of  101.35  per  cent.  The  second  curve  32.5  feet  lower  down  has  an  angle  of  5  degrees, 
and  turns  the  pipe  into  a  grade  of  £4.93  per  cent  on  which  it  is  carried  994.24  feet 


FIG.  i. — Type  of  Penstock  Flange  used  in  recent  Swiss  Practice. 

to  the  last  vertical  curve.  The  latter  has  an  angle  of  40  degrees,  and  from  its  lower 
end  the  pipe  is  carried  along  horizontally  to  the  power  house,  the  total  length  of  the 
main  being  1697  feet. 

The  penstock  is  finished  to  give  it  an  inside  diameter  of  7  feet  6  inches.    At  the  top, 
a  taper,  20  feet  long  and  10  feet  in  diameter  at  the  forebay  entrance,  terminates  in  the 

1  Oxy-hydrogen  Welding.     Electrical  World,  May  9,  1908. 

2  Kern  River  Power  Plant,  by  C.  W.  Whitney.      The  Engineering  Record,  Aug.  10,  1907. 


PENSTOCKS. 


67 


regular  7^  feet  diameter  of  the  completed  tunnel  tube.  This  diameter  of  7^  feet  is 
maintained  throughout  the  inclined  tunnel,  and  on  the  horizontal  beyond  vertical 
curve  No.  3,  for  a  distance  of  167.39  feet. 

At  this  point,  1454.44  feet  from  the  forebay,  the  penstock  emerges  from  the  solid 
rock  and  is  carried  to  the  portal,  a  distance  of  243  feet,  through  a  detrital  deposit, 
lying  between  the  mountain  and  the  power-house  site.  Where  the  tunnel  emerges 
from  the  solid  rock,  a  2o-foot  taper  was  installed,  reducing  the  diameter  of  the  main 
from  7?  to  5^  feet,  at  which  diameter  the  pipe  is  carried  to  the  branch  piping  at  the 
power  house. 


so -*j>o~      so—J 


FIG.  2. — Type  of  Penstock  Flange  used  in  recent  Swiss  Practice. 

The  inclined  part  of  the  pressure  main,  and  the  portion  of  the  horizontal  section 
that  is  carried  through  solid  rock,  were  finished  by  installing  a  steel  lining  built  up 
of  plates  three-sixteenths  inch  thick  for  the  incline,  and  three-eighths  inch  thick  for  the 
horizontal  section,  riveted  together  to  form  a  cylindrical  pipe,  7^  feet  in  internal 
diameter.  The  tunnel  itself  was  driven  in  approximately  circular  form  and  9  feet 
in  diameter.  The  steel  pipe  was  centered  in  the  tunnel,  being  installed  in  lo-foot 
sections,  and  the  space  between  the  outside  of  the  steel  lining  and  the  bed  rock  was 
thoroughly  filled  with  a  mixture  of  i  :  3  :  3  concrete.  The  work  of  installing  this 
lining  was  begun  at  the  lower  end  in  the  horizontal  section,  where  the  pipe  is  tapered 
down  to  a  diameter  of  5^  feet.  At  this  point,  the  2o-foot  taper,  already  mentioned, 
was  placed.  It  consisted  of  if -inch  steel  plates  riveted  together  with  butt  straps. 
The  taper  was  placed  back  in  the  solid  rock,  and  around  it  was  constructed  a  heavy 
bulkhead  of  concrete,  which  was  anchored  into  the  bed  rock  by  means  of  steel  rods 
driven  into  the  sides.  From  this  point,  the  installation  of  the  light  steel  lining  with 
concrete  back-fill,  as  already  stated,  progressed  from  the  bottom  to  the  top  of  the 
tunnel,  terminating  at  the  reinforced  concrete  taper  that  connects  with  the  floor  of 
the  forebay. 

The  rock  formation,  through  which  the  penstock  tunnel  was  driven,  is  not  of  the 
best  kind,  being  very  much  fractured  and  broken.  It  was  necessary  to  timber  the 
greater  part  of  the  shaft  or  incline  when  it  was  excavated,  and  these  timbers  had  to 
be  removed  before  the  steel  lining  was  installed.  The  timbers  were  removed  ahead 
of  the  steelwork,  the  bed  cleaned  off,  and  the  concrete  tamped  into  place  without 
difficulty.  At  a  point  about  120  feet  below  the  top,  the  men  in  charge  removed  some 


68 


HYDROELECTRIC    DEVELOPMENTS   AND    ENGINEERING. 


timbers  without  bracing  the  bents  above.  This  precipitated  a  cave-in  of  the  shaft, 
and  several  men  lost  their  lives,  one  man  being  imprisoned  for  two  weeks,  after  which 
time  he  was  rescued  in  good  condition.  In  retimbering  the  caved  portion,  octagon 
steel  sets  of  y-inch  15 -pound  I-beams  were  used,  these  sets  being  left  in  place 
when  the  concrete  was  filled  in  behind  the  steel  lining. 

The  lower  end  of  the  pressure  main,  below  the  taper  reducing  the  diameter  to 
5^  feet,  was  made  of  if-inch  steel  plates  sufficiently  heavy  to  withstand  the  static 
pressure  without  any  external  support.  No  concrete  was  placed  around  this  pipe, 
and  the  tunnel  was  merely  left  in  its  original  condition  with  the  timber  set  to  support 
the  ground  overhead. 


FIG.  3. — Flange  used  at  the  Brusio  Plant  (i30o-foot.  Head). 


At  a  point  215  feet  above  the  power  house,  a  manhole  was  placed  in  the  inclined 
tunnel  for  convenience  on  inspecting,  and  for  use  in  case  any  repair  work  was  neces- 
sary. The  regular  T\-inch  steel  lining  was  replaced  at  this  point  by  a  section  of 
ij-inch  pipe  30  feet  long. 

The  steel  pipe  was  shipped  to  Camp  No.  i  at  the  power  house  from  San  Fran- 
cisco, in  5-foot  lengths,  5  sections  being  nested  together  for  shipment.  The  outside 
section  was  riveted  complete  on  its  two  longitudinal  seams,  but  the  four  inner  sections 
were  riveted  on  one  seam  only,  so  as  to  allow  for  the  nesting.  At  the  camp,  the  pipe 
was  riveted  into  lo-foot  lengths,  and  hoisted  by  means  of  an  aerial  tram  to  the  forebay 
site  at  the  upper  end  of  the  pressure  tunnel.  There  the  sections  were  secured  to  a 
dolly  car,  and  lowered  by  means  of  a  hoist  to  the  point  where  they  were  to  be  riveted 
together.  This  car  consisted  of  a  truck  at  each  end  of  the  pipe  sections,  the  latter 
being  hung  from  two  timbers  that  passed  through  the  pipe,  and  rested  on  the  axles  of 
the  truck. 

All  the  piping  in  the  pressure  tunnels,  which  is  constructed  of  steel  plates  of 
one-half-inch  thickness  and  under,  is  made  up  with  standard  lap  joints,  double  riveted 


PENSTOCKS.  69 

on  the  longitudinal  seams  and  single  riveted  on  round  seams.  All  pipe  on  the  work 
over  one-half  inch  in  thickness,  is  made  up  of  butt  strapped  joints  throughout,  with 
triple  riveting  on  each  side  of  the  longitudinal  seams,  and  double  riveting  on  each 
side  of  the  round  seams. 

After  the  steel  lining  was  completed,  an  inspection  revealed  the  fact,  that  there 
were  several  places  along  the  bottom  of  the  pipe  where  voids  had  been  formed  in  the 
concrete  backing. 


FIG.  4. — Type  of  Penstock  Flanges  for  Necaxa  Plant,  Mexico. 


These  voids,  which  were  revealed  by  tapping,  were  caused  mainly  by  the  difficulty 
experienced  in  tamping  the  concrete  thoroughly  around  the  steel  lining.  These  steel 
sections  were  10  feet  in  length,  and  in  a  few  places  where  irregular  rock  excavation 
occurred  at  the  bottom  of  a  section,  with  but  a  Q-inch  space  at  the  top  for  handling 
the  tamping  bars,  some  voids  were  naturally  formed  because  of  the  insufficient 
tamping. 

Whenever  these  voids  occurred,  the  pipe  was  tapped  and  liquid  cement  forced  in 
until  the  hole  was  filled.  The  apparatus  designed  on  the  spot  to  accomplish  this 
work  was  an  ingenious  one.  A  section  of  3 -inch  steel  tube  20  inches  long  was  fitted 
at  the  bottom  with  a  cap  that  would  fit  the  hole  drilled  in  the  steel  lining.  Liquid 


HYDROELECTRIC    DEVELOPMENTS   AND    ENGINEERING. 


cement  was  poured  into  the  void  by  means  of  this  pipe,  which  had  a  capacity  of  about 
an  ordinary  pail.  When  no  more  cement  would  run  in,  there  was  fitted  in  the  pipe, 

a  screw  with  a  plunger  at  the  lower  end  and  a 
crank  at  the  outer  end.  By  means  of  this  device, 
the  cement  was  forced  into  the  void  under  pres- 
sure until  it  would  hold  no  more.  The  pump  was 
then  removed  and  the  hole  in  the  lining  was 
stopped  up  by  an  ordinary  flush  pipe  plug.  There 
were  116  of  these  voids  tapped  and  filled  through 
the  lining;  only  three  of  them  were  of  any  size. 
A  number  of  the  voids  required  only  a  pint  of  the 
liquid  cement,  the  quantity  used  varying  up  to  the 

largest,  for  which  ten  buckets  of  the  slush  were  necessary.  The  slush  used  was  a 
liquid  mixture  of  Portland  cement  and  sand.  The  work  was  carried  on  from  a  dolly 
car  fitted  with  beveled  wheels,  lowered  down  from  the  top  by  a  steel  cable.  About 
15  days  were  necessary  to  complete  this  special  work.  After  all  the  voids  were 
filled,  the  entire  pipe  was  painted  with  asphaltum,  the  same  dolly  car  being  used  for 
the  purpose. 


FIG.  5. — Type  of  Penstock  Flange 
for  Sillwerke,  Innsbruck. 


FIG.  6. — Method  of  Anchoring  Penstock,  Jajce  Power  Plant,  Bosnia. 

In  the  rear  of  the  power  house,  a  number  of  branch  penstocks  lead  to  the  turbines. 
They  are  built  tapered,  and  vary  in  thickness  from  if  to  f  of  an  inch.  At  the  end 
of  the  last  section  of  the  penstock  is  a  28-inch  gate  valve  for  emptying  the  entire 
system  when  necessary.  All  branches  are  provided  both  outside  and  inside  of  the 
building  with  a  gate  valve. 


PENSTOCKS. 


Flanges.   In  connection  with  high-pressure  penstocks,  particular  attention  must 
be  paid  to  the  flanges  uniting  the  different  sections.     In  Fig.  4  are  shown  three 
different  designs  of  flanges,  as  used  with  the  pre- 
viously mentioned  Necaxa  penstocks,  for  different 
pressures.     It  will  be  noticed  that  these  flanges 
act  as  a  lever  upon  the  flared  ends  of  the  penstock. 

Another  type  of  flange,  by  the  manufacturer 
of  the  above,  will  be  found  under  subheading 
"Slip-joints.''  A  simpler,  yet  efficient,  flange 
joint  is  seen  in  Fig.  5.  It  has  been  used  in  con- 
nection with  the  Sillwerke  plant,  near  Innsbruck, 
Tyrol.  Its  efficiency  lies  chiefly  in  the  wedge- 
shaped  packing. 

Anchors.  In  order  to  prevent  penstocks  from 
sliding  on  mountain  slopes,  they  must  be 
anchored.  The  simplest  way  is  to  embed  them  in 
concrete  blocks.  Another  way  is  to  rivet  on  iron 
saddles,  and  bolt  the  same  to  concrete  piers;  in 
addition,  anchor  rods  are  sometimes  used.  Such  a  method  of  anchoring  is  seen  in 


UU 


FIG.  7. — Hinged  Penstock  Support, 
Kaiserwerke,  Tyrol. 


t. 


FIGS.  8  and  9. — Expansion  Slip-Joints  for  Penstocks. 

Fig.  6.     By  studying  this  illustration   it  will  be  readily  seen  that  embedding  the 
penstock  in  a  single  massive  block  would  have  accomplished  the  same  purpose. 


72, 


HYDROELECTRIC    DEVELOPMENTS    AND    ENGINEERING. 


Special  precautions  must  be  taken,  where  the  penstocks  run  on  turns,  either 
horizontally  or  vertically,  by  establishing  fixed  anchors.  Between  two  anchors, 
the  penstocks  rest  on  supports,  and  an  expansion  joint  must  be  provided. 

Saddles.  Penstocks  must  be  properly  supported  between  anchors  on  saddles, 
to  allow  the  penstock,  in  case  of  expansion,  to  slide.  As  the  movement  of  the  penstock 
is  slight,  it  is  not  essential  to  provide  the  saddles  with  rollers,  as  has  been  done  in  some 
cases.  The  saddles  are  made  of  cast  iron  or  semisteel,  and  so  designed,  that  the 
penstock  rests  on  two  carrying  surfaces,  in  order  to  give  a  better  support  and  minimize 
friction. 

The  saddles  must  be  rigidly  anchored  to  concrete  or  other  masonry  piers.  The 
spacing  of  the  saddles  is  closer  at  the  bottom  of  the  mountain  slope  than  at  the 
top,  or  they  may  be  constructed  heavier  (similar  to  the  penstocks)  as  the  pressure 
exerted  upon  them  is  greater.  When  the  penstock  leaves  the  ground  for  short 
distances,  a  method  for  supporting  may  be  adopted  as  is  given  in  Fig.  6.  It  has  been 
used  in  connection  with  a  power  plant  in  North  Tyrol.  It  consists  of  a  steel  frame- 
work hinged  to  a  concrete  pier;  the  upper  end  forms  a  saddle,  which  is  clamped 
to  the  penstock.  This  arrangement  allows  a  free  movement  of  the  penstock  due  to 
expansion. 


FIG.  10. — Wedge-Shaped  Expansion 
Joint,  Jajce  Plant,  Bosnia. 


FIG.  ii. — Ferrum  Slip- Joint.     Flange  for  High 
Pressure  Penstocks. 


Expansion  Joints.  The  expansion  joints  must  be  located  at  the  upper  end  of 
each  section  between  anchors,  when  descending  a  mountain  slope.  This  is  done  to 
relieve  the  expansion  joint  from  the  weight  of  the  penstock,  so  that  when  expansion 
takes  place,  the  section  of  the  penstock  slides  up  hill.  These  expansion  joints  are, 
in  most  cases,  of  the  slip-joint  type,  as  seen  in  Figs.  8  and  9,  both  of  which  have 
been  used  in  connection  with  recent  Swiss  power  plants. 

Another  type,  seen  in  Fig.  10,  has  been  used  in  connection  with  the  Jajce  plant 
in  Bosnia.  It  consists  of  a  wedge-shaped  drum  to  take  up  the  expansion  of  the 
penstock,  which  is  laid  on  an  angle.  The  diameter  of  drum  depends  upon  the 
amount  of  expansion  to  be  taken  up,  and  the  sides  are  preferably  of  copper. 


PENSTOCKS. 


A.E.&M.E. 


73 


UNIV.  OF  CAL. 

2  stuffing-hoy 


A  way  to  avoid  special  expansion  joints  and  sliding  saddles,  is  to  us 
flanges,  which  have  been  used  especially  in  high  head  installations.  A  detail  of  this 
flange  joint  is  seen  in  Fig.  n.  The  manufacturers  (Aktiengesellschaft  Ferrum 
Kattowitz,  Germany)  claim  that  it  is  not  essential  to  lay  the  penstock  sections 
exactly  on  centers.  It  does  away  with  slip  joints,  as  each  section  takes  up  its  own 
expansion.  The  joints  can  be  packed  without  taking  the  sections  apart.  Because 
the  flanges  are  removable,  the  sections  are  made  easier  for  shipment,  and  in  some 
cases  they  may  be  telescoped.  Fig.  u  shows  six  penstock  lines  with  this  type  of 


FIG.  12. — Penstocks  with  Slip- Joint  Flanges,  Loch  Leven  Plant,  Scotland. 

flange  as  installed  for  the  Loch  Leven  Water  and  Electric  Company,  Scotland. 
These  penstocks  have  a  diameter  of  40  inches,  and  a  shell'  thickness  varying  from 
three-eighths  to  seven-eighths  inch.  The  lower  sections  are  designed  for  a  pressure 
of  425  pounds  per  square  inch.  Each  of  the  lines  is  6230  feet  long.  The  sections 
are  made  in  19. 7-foot  lengths.  The  concrete  anchor  blocks  are  placed  about 
175  feet  apart. 

The  constant  applied  for  calculating  the  expansion  for  wrought  iron  and  steel  is 
0.0000067  °f  an  mch  Per  inch,  or  approximately  .00008  of  an  inch  per  foot  for  one 
degree  Fahr.  The  coefficient  for  cast  iron  is  .0000059  per  unit  of  length  per  degree 
Fahr.  As  cast  iron  or  cast  steel  fittings  amount  to  but  little,  the  coefficient  of  wrought 
iron  or  steel  is  best  employed. 


74 


HYDROELECTRIC    DEVELOPMENTS    AND   ENGINEERING. 


PENSTOCKS. 


75 


Safety  Devices.  For  the  protection  of  penstocks,  they  must  be  provided  at  the 
upper  end  with  relief  devices.  If  there  is  no  air  vent  at  the  top,  the  penstocks  are 
apt  to  collapse  when  the  head  gates  are  closed,  because  of  the  formation  of  a  partial 
vacuum.  This  vent  pipe  is  nothing  more  than  a  pipe  connection  on  top  and  directly 
behind  the  head  gate,  and  must  extend  above  high-water  level.  Care  must  be  taken 
that  the  vent  pipes  do  not  freeze.  In  many  plants  they  are  simply  ducts  in  the  wall 
of  the  collecting  basin  or  dam.  An  example  of  such  a  device  is  given  in  Fig.  12,  in 
which  case  there  is  a  separate  collecting  basin  and  gate  house.  The  vent  pipes 
extend  through  the  roof  of  the  former  and  above  the  high-water  level  of  the  collecting 


FIG.  14. — Automatic  Flap.     Inlet  to  Penstock,  Brusio  Plant,  Switzerland. 


basin.  Another  safety  device  in  the  head  works  of  this  plant  is,  the  mouth  of  the 
penstock  in  the  collecting  basin  is  provided  with  a  flap  valve.  In  case  a  penstock 
should  fail,  this  valve  will  close  automatically,  and  can  be  operated  from  the  collecting 
basin  or  from  the  power  house  by  remote  control.  The  flap  is  counterbalanced  by  a 
weight.  The  penstocks  can  be  filled  through  a  by-pass  after  the  flap  is  closed  (see 
Fig.  14).  In  addition  to  this,  the  collecting  basin  is  provided  with  a  mechanical- 


76  HYDROELECTRIC    DEVELOPMENTS   AND   ENGINEERING. 

electric  water-level  indicator,  which  indicates  in  the  power  house  the  water  level  in 
the  collecting  basin. 

Another  device  for  admitting  air  into  a  penstock  to  prevent  the  formation  of  a 
vacuum,  is  shown  in  Fig.  15.  It  has  been  installed  in  a  recent  Swiss  power  plant, 
which  operates  under  a  head  of  767.5  feet.  When  the  penstock  is  under  pressure, 
the  valve  is  closed;  when  air  is  admitted,  the  disk  is  held  in  place  by  a  spring.  In 
plants  where  the  penstocks  have  a  long  horizontal  run,  and  suddenly  go  down  a  steep 
slope,  a  vacuum  will  be  created  in  the  latter  if  the  turbine  valve  is  suddenly  opened 
wide.  This  is  due  to  the  fact  that  the  velocity  will  be  greater  in  the  vertical  section 
than  in  the  long  horizontal  line.  To  overcome  this,  the  above-mentioned  valve  is 
placed  near  the  junction  of  the  vertical  and  horizontal  sections. 

Fig.  15  is  another  safety  device,  which  will  act  automatically  on  low-water  level, 
or  in  case  the  generator  should  drop  its  load.  If  for  any  reason  the  penstock  should 
fail,  the  valve  will  shut  off  the  water  automatically. 

The  lower  end  of  the  penstocks  must  be  provided  with  relief  valves  or 
blow-out  plates,  so  that  in  case  of  a  sudden  shut  down  of  the  turbines,  the  water 
in  the  penstock  will  be  released  through  the  safety  devices,  and  discharged  into 
the  tailrace. 

The  safety  devices  must  be  so  located,  that  when  they  operate,  no  damage  will 
result.  Manholes  must  be  provided  on  the  lower  sections  of  penstocks. 

Standpipes.  Another  safety  device,  to  relieve  penstocks  of  excess  pressure,  is  the 
standpipe.  These  standpipes  are  usually  connected  to  the  end  of  the  penstock,  and 
must  extend  vertically  several  feet  above  the  head,  so  that  in  case  of  a  sudden  increase 
of  pressure,  the  water  has  a  chance  to  rise  before  overflowing.  Usually  these  stand- 
pipes  are  wasteful,  and  to  overcome  this  defect,  a  standpipe  system  similar  to  that  in 
the  Urfttalsperre,  Germany,  may  be  used.  This  standpipe,  however,  is  not  located 
at  the  end  of  the  penstock,  but  lies  at  the  junction  of  the  pressure  tunnel  and  the 
penstock. 

Another  method  is  to  provide  the. lower  end  of  the  penstock  with  an  air  cushion, 
which  is  nothing  more  than  a  closed  chamber,  and  acts  in  the  same  way  as  an  air 
chamber  on  a  reciprocating  pump.  This  air  chamber  must  be  as  air  tight  as  possible, 
otherwise  the  air  will  escape  and  render  the  device  useless.  In  connection  with 
Jajce  Power  Plant,  Bosnia,  1899,  the  author  experienced  similar  trouble,  and  to 
remedy  the  difficulty,  an  air  pump  had  to  be  installed  to  maintain  the  air  cushion. 
All  standpipes  must  be  protected  from  freezing. 

Protection.  In  exceptionally  cold  regions,  penstocks  must  be  protected  from 
frost.  They  may  be  embedded  in  the  ground  below  the  frost  line,  or  protected  by 
a  wooden  box  covering.  To  cite  an  example  what  frost  might  do,  at  Grand  Mere, 
Quebec,1  a  penstock  of  14  feet  diameter  was  left  unprotected  during  the  first  winter. 
It  was  found  to  have  its  interior  surface  covered  with  solid  crystal  ice  of  from  12  to 
18  inches  in  thickness. 

If  the  penstock  is  buried  in  the  ground,  the  trench  must  be  left  open  at  least 
several  months  after  operation  has  commenced,  to  ascertain  whether  additional 

1  Thurso,  Modern  Turbine  Practice,  p.  176. 


PENSTOCKS. 


77 


O. 

S 

a 


I 


o 
-o 

S 


HYDROELECTRIC    DEVELOPMENTS    AND    ENGINEERING. 


calking  is  necessary.     Before  the  trench  is  filled,  the   penstock   must   be   properly 
painted.     Buried  penstocks  do  not  require  any  device  for  taking  up  expansion. 
All  penstocks  must  be  coated  with  hot  asphalt  both  inside  and  outside. 

WOODEN    PENSTOCKS. 

Adaptability.    Wooden  penstocks  are  largely  used  in  the  western  states,  particu- 
larly on  the  Pacific  coast,  where  it  is  necessary  to  conduct  water  over  long  runs. 

They  are  practically  installed  for  heads 
up  to  300  feet.  Wherever  they  are 
installed  under  higher  heads,  they  are 
always  placed  in  the  top  section  of  the 
conduit.  As  they  have  many  advantages 
over  metal  or  reinforced  concrete  pen- 
stocks, they  are  much  in  favor.  Some 
of  the  advantages  are,  that  they  are 
smooth  and  have  a  greater  carrying 
capacity,  ranging  from  10  to  20  per  cent 
more  than  any  other.  Another  import- 
ant factor  is,  that  they  are  very  much 
cheaper  and  do  not  deteriorate  as  rapidly 
as  those  of  metal.  Further,  they  are 
unaffected  by  frost. 

In  the  construction  of  some  pen- 
stock lines,  it  would  be  difficult  to 
transport  heavy  steel  penstocks  over  the 
country  where  there  are  no  roads.  In 
such  cases,  the  wooden  penstock  is 
used.  They  range  in  diameter  from 
10  inches  upward,  and  vary  in  thickness 
according  to  the  diameter.  The  staves 
are  milled  from  clear,  well-seasoned  or 
kiln-dried  yellow  pine,  redwood  or  fir. 
The  ends  of  the  staves  are  connected 
by  a  tongue,  which  prevents  butt  joint 
leakage.  The  staves  are  held  in  place 
by  steel  rods  and  a  cast-iron  shoe. 


FIG.  16. — Automatic  Low  Water  Device  for 
Protecting  Penstocks. 


Spacing  of  Bands.    The  spacing  of  the  iron  bands  is  determined  by  a  formula 


given  by  James  D.  Schuyler.1 


N  = 


1200    DP 

28 


N  =  number  of  bands  per  100  feet. 
D  =  diameter  of  pipe  in  inches. 
P  =  pressure  in  pounds  per  square  foot. 

S  =  safe  working  strain  in  pounds  per  square  inch  for  bands  when  threaded 
for  use,  determined  by  regular  tests  at  the  mills  where  they  are  made. 

1  Trans,  of  Am.  Soc.  of  C.  E.,  vol.  xxxi. 


PENSTOCKS. 


FIG.  17. — 84-inch  Wooden  Stave  Penstock,  3700  feet  long,  joined  to  two  60- inch  Riveted 
Steel  Penstocks,  each  800  feet  long.     Trenton  Falls  Water  Power  Plant,  Utica,  New  York. 

The  following  values  of  5  give  a  factor  of  safety  of  about  five  in  each  case,  or 
about  one-fourth  of  the  elastic  limit : 

TABLE    I. —  SAFE    WORKING    STRAIN    OF    PENSTOCK    BANDS. 


f-inch  bands  

plain 

S  =  1000  pounds. 

f-inch  bands  

upset 

.S  =  1  200  pounds. 

^-inch  bands  .  . 

plain 

5  —  2000  pounds. 

£-inch  bands  
f-inch  bands  
f-inch  bands.  .... 

upset 
plain 
upset 

5=  2500  pounds. 
5=  3000  pounds. 
5=  3500  pounds. 

The  formula  given  below  was  used  by  C.  P.  Allen,  in  the  construction  of  a 
6^-mile  penstock  along  the  Little  Conemaugh  River  near  Johnstown,  Penn.  This 
penstock  has  a  diameter  of  36  to  44  inches.  The  pressure  in  this  penstock  is  slight; 
the  regular  slope  is  i  to  2  feet  in  looo.1 

1  Some  Applications  of  Wooden  Stave  Pipe,  by  John  Birkinbine,  in  a  paper  before  the  Engineers'  Club, 
Philadelphia,  Penn. 


8o 


HYDROELECTRIC    DEVELOPMENTS    AND   ENGINEERING. 


Number  of  bands  per  100  feet  = 


600  DPHF 
AB 


D  =  diameter  of  pipe  in  inches. 
P  =  pressure  due  to  i  foot.     (0.44  pound.) 
H  =  head  in  feet. 
F  =  factor  of  safety. 
A  =  area  of  bands  in  square  inches. 
B  =  breaking  strain  of  bands  per  square  inch. 

Thus,  for  a  44-inch  penstock,  one-half  inch  bands,  and  a  5o-foot  head,  the 
number  of  bands  per  100  feet  is 

600  X  44  X  0.44  X  50  X  4 

-   =  197. 
0.19635  X  60000 

Friction.  As  already  indicated,  the  friction  in  wooden  penstocks  is  very  low,  as 
the  staves  are  planed.  The  resistance  of  steel  penstocks  increases  each  year,  while 
that  of  wooden  penstocks  decreases.  In  Kutter's  formula,  the  factor  of  resistance 
is  generally  taken  as  o.oio  for  wooden  stave  pipe,  while  for  steel  as  0.013.  Some- 
times the  factor  for  wooden  stave  penstocks  goes  as  low  as  0.007. 


FIG.  18. — Three  7-foot  Wooden  Stave  Penstocks,  each  4000  feet  long  and  connected  to 
Riveted  Steel  Penstocks,  1000  feet  long.  Great  Northern  Power  Company,  Duluth, 
Minnesota. 

Durability.   The  durability  of  wooden  stave  penstocks  if  kept  continually  wet, 
is  yet  undetermined.     The  following  data  are  of  interest:  in  1898  some  of  the  original 


PENSTOCKS. 


81 


wooden  pipe  laid  in  the  London  waterworks  in  1802,  were  taken  out  sound  and  free 
from  rot.  Some  of  these  wooden  mains  were  in  actual  use  as  late  as  1865,  after 
having  been  in  the  ground  for  63  years.  Some  of  the  wooden  pipes  first  laid  in 
Philadelphia,  after  being  in  use  21  years,  were  removed  and  relaid  in  Burlington 
where  they  were  in  use  for  28  years. 

In  a  series  of  tests  carried  on  at  the  Puget  Sound  Navy  Yard  in  1901,  comparing 
Douglas  fir  and  yellow  pine  for  pipe  staves,  Frank  W.  Hibbs,  naval  constructor 
of  the  United  States  Navy,  arrived  at  the  following  conclusions: 

In  strength,  Douglas  fir  is  generally  equal  to  yellow  pine,  and  superior  to  it  in 
some  essential  particulars. 

Douglas  fir  is  decidedly  more  elastic  than  yellow  pine. 

Douglas  fir  is  far  superior  to  yellow  pine  as  regards  toughness. 

Yellow  pine  is  superior  to  Douglas  fir  in  wearing  qualities,  especially  when 
moisture  is  present. 

Yellow  pine  is  superior  to  Douglas  fir  in  lasting  qualities,  on  account  of  the 
greater  amount  of  pitch  it  contains. 

Douglas  fir  is  14  per  cent  lighter  than  yellow  pine. 

Following  are  the  average  general  characteristics  of  strength  of  Douglas  fir: 

For  well-seasoned,  fine-grained,  hard,  clear  stock: 

TABLE    II. —  STRENGTH    OF    DOUGLAS    FIR. 


Characteristics. 

Pounds  per 
square  inch. 

Tensile  strength  

13,000 

Tensile  strength  across  grain  

•3CO 

Tensile  strength  for  bending  

10,000 

Elastic  limit  for  bending  

6,000 

Modulus  of  elasticity  for  bending  

1,500,000 

Strength  for  compression  across  the  grain  without 
destructive  deformation  

1,200 

Modulus  of  elasticity  for  compression  across  the  grain. 
Crushing  strength  for  compression,  "end  on"  to  grain 
Modulus  of  elasticity  for  "end  on"  compression  
Modulus  of  elasticity  for  torsion  

4,000 
9,000 
70,000 
27,000 

Shearing  strength  with  the  grain  

15,000 

Crushing  strength  for  columns  whose  proportions  are 
such  as  to  resist  bending  

6,000 

^Veight  per  cubic  foot,  pounds  .  . 

7C 

Cost.  The  cost  of  wooden  stave  penstocks  relative  to  steel  penstocks,  depends 
on  pressure,  size,  location,  and  character  of  country,  through  which  they  are  laid. 
Mr.  L.  A.  Adams  states  that  the  details  of  cost  of  an  i8-inch  penstock  at  Astoria, 
Ore.,  7^  miles  long,  are  as  follows: 

"  Steel  in  bands,  $0.048  per  pound;  lumber,  feet  board  measure  in  staves  measured 
before  milling,  $35.40  per  thousand.  The  cost  to  the  city,  including  all  appurte- 
nances, was  $0.903  per  foot;  and  $0.76  excluding  such  appurtenances.  The  whole 
amount  of  the  contract  was  $36,100,  and  the  total  extra  work  cost,  $29.35. 


82 


HYDROELECTRIC    DEVELOPMENTS    AND    ENGINEERING. 


The  distribution  of  the  cost  was  as  follows: 

"Building  and  spacing  bands,  55  per  cent;  back-cinching,  26  per  cent;  repainting 
ironwork,  3  per  cent;  back-filling  to  a  depth  of  6  inches  over  the  pipe,  8.75  per  cent; 
placing  specials,  3.5  per  cent;  placing  air  valve,  0.75  per  cent;  unclassified  labor, 
3  per  cent." 


f 


FIG.  19. — Cross  Section  and  Partial  Plan  of  a  Wooden  Stave  Penstock. 
Adams  also  gives  the  cost  for  the  riveted  steel  pipe  in  the  same  line  as  follows: 


Size. 

Gauge  of  steel. 

Price. 

14-inch 
1  6-inch 
1  6-inch 

No.  12 
No.  12 
No.  10 

$1.  IO 

1.18 
1.38 

The  manufacturing  cost  of  the  riveted  steel  pipe  was  about  0.45  of  a  cent  per 
pound  for  labor  only,  including  the  cost  of  dipping. 


FIG.  20. — Cast-Iron  Saddle  for  Connection  to  a  Smaller  Pipe. 


Comparative  costs  on  the  construction  of  steel,  cast-iron  and  wooden  penstocks 
are  given  in  Table  III,  as  compiled  by  Mr.  A.  L.  Adams  for  Chicago.  These  figures 
are  supposed  to  include  only  the  principal  items,  with  no  profit  to  the  contractor, 
or  for  incidentals,  and  are  therefore  for  comparison  only. 


PENSTOCKS. 


TABLE  III.  —  COMPARATIVE  COST  OF  PIPE  AT  CHICAGO,  INCLUDING  LAYING,  BUT 

OMITTING    HAUL. 

Wooden  Stave  Pipe. 


Diameter. 

2  5  -foot 

head. 

So-foot 

head. 

loo-foot  head. 

2oo-foot  head. 

Inches  . 

12 

18 
24 
3° 
36 
42 
48 

54 
60 
66 
72 

$0.42 

o.  69 

0.79 

o.  96 

1.19 

1.40 

i-55 
2.23 
2.85 
3.21 
3-65 

$0.49 
0.8o 
0.91 
I.  12 
1.40 

1.68 
1.85 

21  62 

3-35 
3.81 

4-38 

$0.63 
1.02 
I.I4 
1.44 
1.82 
2.23 
2.  46 

3-43 
4-37 
5.00 

5-83 

$0. 

i. 
i. 

2. 
2. 

3- 
3- 
5- 
6. 

7- 
8. 

85 
46 
61 
06 
65 
33 
67 

02 

40 

38 

73 

Riveted  Steel  Pipe. 

Diameter. 

No.  14. 

No.   12. 

No.   10. 

No.  8. 

No.  6. 

J-inch. 

T^-inch. 

f-inch. 

Inches. 

12 

18 
24 
30 
36 
42 
48 

54 
60 
66 
72 

$0.32 

$0.38 
o-57 

$0.44 
0.65 
0.85 

$0.78 
1.04 
1.27 

i-55 
1.61 

$0.98 
1.28 
i-59 

1-93 

2.18 
2.48 
2.80 

$i-55 
i-93 
2.30 
2.66 
3-°3 
3-4i 
3-79 
4-35 
4-52 

$1.99 
2.46 
2.92 
3-37 
3-83 
4.29 

4-75 

5-21 

5.66 

$3.04 

3-58 
4.12 
4.66 
5.21 

5-74 
6.  29 
6.83 

Cast-Iron  Pipe. 

Diameter. 

2  5  -foot  head. 

•5o-foot 

head. 

ioo-foot  head. 

zoo-foot  head. 

Inches. 

12 

18 

24 

3° 
36 
42 
48 

54 
60 
66 

72 

$0.73 
1.29 
1.91 
2.  67 

3-47 
4.42 

5-5° 
6.65 
8.04 

9-Si 
11.32 

$0. 

I. 

2. 
2. 

3- 
4- 
5- 
7- 
8. 
10. 

12. 

77 
35 

00 

80 

67 
69 

84 

10 

63 

16 

oo 

$0.84 
1.46 
2.18 

3-°7 
4.06 

5-22 
6-53 

8.00 
9.80 

11-55 
13.26 

tOfr 

51  . 
I. 
2 

3- 
4- 
6. 

7- 
9- 

12. 
14. 

16. 

00 

70 

55 
61 

85 
28 
92 
78 
13 
°5 
oo 

84  HYDROELECTRIC    DEVELOPMENTS   AND   ENGINEERING. 

\ 

Construction.    A  very  good  example  of  wooden  stave  pipe  construction  is  that 

built  in  connection  with  the  Bishop  Creek  Power  Plant.1  The  penstock  is  about 
12,000  feet  long,  consisting  of  6700  feet  of  42-inch  wood-stave  pipe,  2150  feet  of 
30-inch  wood-stave  pipe,  and  3150  feet  of  24-inch  steel  penstock;  all  diameters 
being  inside  measurements.  The  42-inch  penstock  lies  on  a  nearly  level  grade,  the 
static  head  at  the  lower  end  being  about  30  feet.  At  this  point,  are  placed  two 
3O-inch  gate  valves,  one  opening  into  the  30-inch  penstock,  and  the  other  provided  for 
a  future  line.  The  30-inch  penstock  descends  the  hill  to  a  point  that  gives  a  static 
head  of  265  feet.  Here  it  joins  the  24-inch  steel  penstock,  which  descends  a  steep 
hill  to  the  power  house;  the  total  static  head  is  1068  feet.  For  about  500  feet,  this 
steel  penstock  is  laid  on  an  angle  of  38  degrees  from  the  horizontal. 

The  42-inch  penstock  is  made  up  of  twenty-five  staves,  and  the  3O-inch  penstock 
of  nineteen  staves,  milled  from  a  2  by  6-inch  piece.  The  lumber  is  red  fir  from 
Southern  Oregon,  and  the  staves  were  milled  there  to  the  proper  circle.  The  bands 
are  mild  steel,  one-half  inch  in  diameter,  with  ends  upset  to  five-eighths  inch  diameter. 
They  were  shipped  straight,  and  bent  to  form  at  the  work.  The  lugs  are  of  cast 
iron,  of  a  form  that  allows  the  ends  of  the  bands  to  pass  each  other,  and  be  tightened 
with  nuts  on  each  end. 

When  the  bands  are  tightened  there  is  a  slight  bending  of  the  rods,  but  this  is  not 
believed  to  be  injurious.  The  ends  of  the  staves  were  slotted,  and  a  three-sixteenths 
by  one-half  inch  compressed  paper  dowel  inserted.  When  wet,  this  dowel  swells,  and 
proves  very  effective  in  closing  leaks.  Bands  on  the  42-inch  penstock  were  spaced 
on  6-inch  centers,  although  the  pressure  did  not  demand  this  close  spacing.  On  the 
3O-inch  pipe,  which  is  subject  to  a  considerable  pressure,  the  designer  used  the 
pressure  due  to  swelling  of  wood  given  by  A.  L.  Adams,  100  pounds  per  square  inch; 
in  addition  to  this,  an  allowance  was  made  for  initial  tension  in  the  rods  due  to  the 
stress  necessary  to  bring  the  staves  into  form.  Red  fir  is  a  very  stiff  wood,  and  by 
observation  it  was  determined  necessary  to  use  2100  pounds  to  bring  the  staves 
into  position;  this  was  calculated  as  being  distributed  along  the  lineal  foot  of  pipe, 
and  distributed  among  whatever  number  of  bands  occurred  in  that  length  under 
different  heads.  Bands  were  spaced  under  these  assumptions  with  a  safety  factor 
of  four. 

The  question  of  initial  tension  on  the  rods  is  believed  to  be  a  vital  one,  as,  in  the 
case  of  the  stiff  lumber  used,  it  required  much  cinching  to  make  the  staves  come 
together.  As  the  wood  is  hard,  the  bands  crushed  into  it  but  little  under  pressure, 
and  hence  there  is  little  relief  to  the  stress.  By  test  it  was  determined,  that,  with  the 
wrenches  used,  an  initial  tension  of  8000  pounds  per  square  inch  could  easily  be 
obtained. 

The  wood  pipe  is  laid  directly  on  the  ground,  a  few  sills  of  culled  material  being 
placed  at  intervals.  At  points,  it  was  covered  with  earth  as  a  protection  from  possible 
rocks  rolling  down  the  steep  hillsides.  The  penstock  was  laid  in  easy  curves,  but  in 
one  case  a  curve  of  100  feet  radius  was  made  through  nearly  90  degrees.  For  nearly 
two  months  the  daily  amount  laid  averaged  no  feet. 

1  Bishop  Creek,  Cal.,  Hydro-electric  Power  Plant,  by  J.  D.  Galloway.   Electrical  World,  June  30,  1906. 


PENSTOCKS.  85 

The  wood  pipe  is  provided  with  two  6-inch  and  one  3o-inch  standpipes,  the 
former  being  of  casing  and  the  latter  of  3O-inch  wood  pipe.  In  addition,  6-inch  air 
valves  are  supplied  in  such  number,  that  there  is  a  6-inch  opening  every  noo  feet. 
On  the  steel  pipe,  three  6-inch  air  valves  were  placed  at  the  upper  end.  The  material 
for  the  wood  pipe  was  mostly  hauled  to  the  site  on  wagons,  a  minor  portion  being 
hauled  up  from  the  power  house  on  the  tramway  used  in  laying  the  steel  pipe. 

Another  very  interesting,  and  in  some  respects  difficult,  wooden  stave  penstock 
construction  was  laid  in  the  American  Fork  Canyon,  Utah.1  Where  conditions 
justified,  the  continuous  wood-stave  penstock  was  laid  on  a  grade  as  near  the  hydraulic 
grade  as  was  thought  advisable,  when  considering  the  necessity  of  keeping  the  pipe 
filled.  It  was  found  necessary,  however,  to  construct  three  inverted  siphons,  the  first 
and  longest  one  being  at  the  upper  end  of  the  line,  where  the  pipe  follows  down  the 
bottom  of  the  canyon  for  some  distance;  the  other  two  are  about  midway  between  the 
point  of  diversion  and  the  power  house.  The  maximum  head  on  this  pipe,  at  one  of 
the  siphons,  is  175  feet. 

The  remaining  portion  of  this  line  was  laid  on  a  table,  cut  on  a  grade  contour  along 
the  mountain  side.  As  the  canyon  is  rough  and  broken,  this  alignment  necessitated 
the  introduction  of  many  curves,  some  of  which  were  quite  sharp,  and  the  driving  of 
many  tunnels  through  solid  quartzite  ledges,  the  length  of  the  tunnels  varying  from 
25  to  1 60  feet.  The  tunnels  were  rectangular  in  shape,  the  dimensions  being  4  by 
5  feet,  and  some  of  them  were  located  on  curves. 

The  pipe  is  36  inches  in  diameter,  and  a  section  at  right  angles  to  its  axis  shows 
22  staves.  These  staves  were  sawed  from  well-seasoned  Oregon  fir,  with  their  faces 
dressed  to  true  segments  of  circles,  and  the  edges  to  true  radial  lines.  They  are 
if  inches  thick,  but  vary  in  length  from  8  to  15  feet. 

In  making  the  joints,  a  special  malleable  casting  patented  by  Frank  C.  Kelsey 
was  used.  A  section  through  this  casting  is  similar  in  shape  to  that  of  an  I-beam, 
except  that  there  is  a  shorter  flange  projecting  from  the  middle  of  the  web  on  either 
side.  The  distance  between  the  outer  edges  of  the  main  flanges  corresponds  with 
the  thickness  of  the  staves,  but  one  of  them  has  a  batter  of  one-thirty-second  inch. 
This  means,  that  when  in  place,  the  outer  flanges  project  over  the  ends  of  the  stave, 
compressing  it  one-thirty-second  inch,  while  the  middle  triangular  flanges  are  driven 
into  them.  The  flanges  of  this  casting  are  longer  than  the  web,  so  they  not  only 
project  over  the  two  ends  of  the  staves,  but  also  over  the  side  adjoining. 

The  bands  are  one-half  inch  in  diameter  and  have  square  heads,  with  upset 
threaded  ends.  The  foreman  on  the  work  was  provided  with  a  sheet  showing  the 
required  band  spacing  for  the  various  portions  of  the  pipe,  the  spacing  having  first 
been  calculated  for  the  given  pressure. 

The  coupling  has  a  curved  seat,  which  sets  on  the  outside  of  the  stave,  and  two 
lugs  so  designed  that  they  will  hold  both  the  head  and  nut  of  the  band. 

The  staves  were  hauled  as  near  to  the  work  as  possible  in  wagons.  From  this 
point,  in  the  bottom  of  the  canyon,  a  narrow  T-rail  track  was  laid  up  the  mountain 

1  An  Hydro-electric  Development  in  American  Fork  Canyon,  Utah,  by  A.  P.  Merrill.  The  Engineer- 
ing Record,  May  9,  1908. 


86  HYDROELECTRIC    DEVELOPMENTS    AND   ENGINEERING. 

side  to  the  grade.  The  cars  containing  the  bands,  staves,  and  so  forth,  were  drawn 
up  the  track  by  a  horse. 

All  castings  and  steel  bands  were  dipped  in  a  special  paint  before  being  used. 
This  was  done  in  the  bottom  of  the  canyon  near  the  lower  end  of  the  track. 

Construction  was  quite  difficult  in  many  places,  especially  at  the  two  lower  siphons, 
and  in  the  tunnels  located  on  the  curves.  In  building  the  pipe  around  curves,  short 
straight  lengths  from  50  to  75  feet  long  were  first  constructed,  only  enough  bands 
being  used  to  hold  the  staves  in  place.  It  was  then  shifted  into  the  proper  place  with 
jacks.  In  doing  this,  some  of  the  staves  tended  to  slide  longitudinally,  which  condi- 
tion required  driving  them  to  place,  from  the  end  of  the  pipe,  with  heavy  mallets. 
The  rest  of  the  required  number  of  bands  were  then  placed. 

When  the  bapds  were  first  placed  around  the  dry  staves,  they  were  made  just 
tight  enough  to  hold  the  pipe  together.  After  the  water  had  been  turned  in,  and  the 
staves  had  become  fairly  well  saturated,  all  bands  were  tightened.  But  at  no  time 
were  they  drawn  so  tight  that  the  fiber  of  the  wood  was  cut  or  crushed.  The  second 
tightening  of  the  bands  stopped  practically  all  leaks,  there  being  none  in  the  two 
miles  of  pipe  of  any  importance,  and  only  a  small  number  of  minor  ones  where  the 
pressure  was  highest. 

Air  vents  or  standpipes  were  placed  at  all  summits,  and  washout  valves  at  the 
lowest  point  in  the  siphons.  Much  of  the  sediment  that  succeeds  in  passing  the  head- 
works  will  settle  in  the  siphons,  where  it  can  be  washed  out,  and  its  deteriorating 
effects  on  the  machinery  avoided. 

REINFORCED  CONCRETE  PENSTOCKS. 

The  reinforced  concrete  penstock  has  not  been  used  to  a  great  extent,  although, 
in  some  French  plants,  they  have  been  used  for  many  years  under  low  heads,  and  are 
made  in  one  continuous  piece  by  hand. 

A  newer  process  (System  Siegwart)  has  been  developed  in  Switzerland,  whereby 
penstocks  of  reinforced  concrete  can  be  made  by  machinery,  and  capable  of  carrying 
pressures  up  to  300  pounds  and  higher,  if  desired.  The  thickness  of  the  shell  is  a 
matter  of  requirements  to  suit  the  conditions  at  hand. 

Being  manufactured  by  automatic  machinery  of  very  compact  design,  the  pen- 
stocks can  be  readily  made  in  the  field.  They  are  made  in  sections,  the  length  of 
which  depends  on  the  size  of  the  machine.  The  ends  are  provided  with  special  joints, 
which,  after  in  place,  are  filled  with  asphalt.  To  insure  further  tightness,  an  external 
band  is  slipped  over  the  joint,  and  sealed  by  the  asphalt. 

After  coming  from  the  machine,  the  penstock  sections  are  coated  inside  with  a 
layer  of  asphalt.  This  treatment  renders  the  penstock  absolutely  water  tight,  and,  in 
addition,  reduces  the  skin  friction,  which  means  an  increase  in  head  above  the 
ordinary  concrete  penstock. 


PENSTOCKS. 


BIBLIOGRAPHY. 


A.E.&M.E. 

87 
UNIV.  OF  C 


EXPERIMENTAL  STUDY  OF  THE  RESISTANCE  OF  THE  FLOW  OF  WATER  IN  PIPES.    A.  V.  Saph  and  E.  W. 

Schoder.     Proc.  A.  S.  C.  E.,  May,  1903. 

FLOW  OF  WATER  IN  WOODEN  PIPES.    T.  A.  Noble.     Trans.  A.  S.  C.  E.,  vol.  49,  1902. 
FLOW  OF  WATER  IN  PIPES.     C.  H.  Fulton.    Journal  Association  Engineering  Societies,  October,  1899. 
FRICTION  COEFFICIENT  OF  RIVETED  STEEL  PIPES.    A.  McL.  Hawks.    Proc.  A.S.C.  E.,  August,  1899. 
A  TRAVELING  MOLD  FOR  MAKING  REINFORCED  CONCRETE  PIPES.    F.  Teichman.    Engineering 

News,  Feb.  20,  1908. 

PIPE  LINES  FOR  HYDRAULIC  PLANTS.    Engineering  Record,  Dec.  21,  1907. 

A  DIAGRAM  FOR  CALCULATING  PENSTOCKS.    Richard  Muller.    Engineering  Record,  Nov.  14,  1908. 
PENSTOCKS  FOR  WATER  POWER  PLANTS.    Frank  Koester.     Engineering  Record,  Feb.  20,  1909. 
WOODEN  STAVE  vs.  RIVETED  PIPE.     Journal  Association  Engineering  Societies,  p.  239.     1898. 
STAVE-PIPE.    A.  L.  Adams.     Trans.  A.  S.  C.  £.,  p.  676.     1898. 


CHAPTER   V. 
POWER   PLANT. 

GENERAL    ARRANGEMENT. 

HYDRAULIC  power  plants  have  no  standard  arrangement,  as  there  are  so  many 
types  of  turbines  which  are  fed  under  various  conditions;  low  heads  may  be  utilized 
by  horizontal  or  vertical  turbines,  requiring  an  entirely  different  proposition  in  the 
layout  of  the  plant.  The  same  is  true  for  average  as  well  as  high  head  turbines;  even 
in  the  latter  case,  which  usually  requires  horizontal  impulse  wheels,  vertical  impulse 
wheels  are  sometimes  used.  Whatever  arrangement  is  chosen,  care  should  be 
exercised  to  locate  the  turbines  so  as  to  secure  the  highest  possible  head.  Many  tur- 
bines are  dependent  upon  draft  tubes  to  give  additional  heads.  The  turbines  and 
regulators  should  be  set  in  straight  lines,  and  not  scattered  about  the  generating 
room.  This  also  applies  to  high  head  turbines  which  are  sometimes  set  on  45  degrees, 
which  is  done  to  give  a  more  easy  penstock  connection.  Such  arrangements  can  be 
easily  overcome  by  exercising  a  little  judgment,  and  with  little  or  no  expenditure  of 
money.  This  must  be  done  for  the  sake  of  the  appearance  of  the  plant,  and,  of  still 
greater  importance,  ease  of  operation.  Whatever  arrangement  is  decided  upon,  the 
flow  of  water  to  the  turbines  should  be  as  free  and  easy  as  possible,  to  avoid  friction. 

Heads  utilized  vary  very  greatly.  At  Genoa,  Switzerland,1  is  a  plant  utilizing  a 
head  of  16.5  inches,  while  at  Vouvry  on  Lake  Geneva,  Switzerland,  there  is  a 
2o,ooo-HP.  plant  operating  under  a  head  of  3116  feet.2 

From  the  foregoing  figures,  it  will  be  seen  that  it  is  impossible  to  delineate  the 
different  designs  of  plants  operating  under  various  heads  and  conditions.  In  the 
following  pages,  only  a  few  typical  arrangements  of  low,  medium  and  high  head  plants 
are  discussed.  In  low  and  medium  plants,  the  power  house  frequently  forms  a  part 
of  the  dam,  or  adjoins  the  dam  on  the  downstream  side,  or,  in  the  case  of  a  hollow 
concrete  dam,  is  located  in  the  body  of  the  dam.  In  any  case,  the  walls  must  be  made 
waterproof  to  prevent  seepage  leaking  into  the  power  house. 

Forebays.  Forebays  must  be  located  so  as  to  deflect  all  foreign  material  as  much 
as  possible.  This  is  best  done  by  placing  the  deflecting  wall  at  an  angle  of  30  to 
45  degrees  to  the  flow  of  the  stream.  This  wall  extends  2  or  3  feet  into  the  water. 
Below  the  water  level  and  fastened  to  the  deflecting  wall  are  rough  screens,  which  in 
large  plants  consist  of  heavy  bars.  The  forebay  itself  should  be  provided  with  a 
spillway,  icerun  and  a  sandtrap.  The  latter  is  best  located  just  before  the  water 
enters  the  penstock.  The  bottom  of  the  forebay  must  slope  towards  the  sandtrap, 

1  Thurso,  Modern  Turbine  Practice,  p.  13.  2  Wagenbach,  Turbinenanlagen,  p.  3. 


POWER  PLANT. 


89 


FIG.  i. — Winnipeg,  Manitoba,  Plant. 


FIG.  2.— Cross  Section  of  Albany,  Georgia, Plant. 


FIG.  3.— Cross  Section  of  Low  Head  Plant,  Holyoke  Water  Power  Company,  Holyoke, 

Massachusetts. 


9o 


HYDROELECTRIC    DEVELOPMENTS    AND    ENGINEERING. 


to  decrease  the  velocity  of  approach,  and  to  give  the  sand  and  gravel  an  opportunity 
to  settle.  There  must  be  an  opening  on  the  spillway  side,  to  carry  off  the  stuff  which 
has  collected  in  the  trap.  The  penstocks  must  be  provided  with  fine  screens  located 
above  the  sandtrap  and  in  front  of  the  penstock  openings.  In  large  plants,  the 
screens  and  gates  to  the  penstocks  are  usually  placed  in  a  house  by  themselves,  which 
is  provided  with  a  crane  to  remove  and  lower  screens.  In  temperate  zones,  it  is 
advisable  to  install  a  heating  system  in  the  screen  and  gatehouse,  for  the  prevention 
and  thawing  of  ice. 

The  design  and  arrangement  of  the  forebay,  in  connection  with  the  power  house, 
depend  upon  nature  and  character  of  stream,  particularly  on  the  nature  of  the  floating 
material;  also  the  formation  of  ice  is  an  important  factor  in  this  consideration. 


FIG.  4. — General  Plan  of  Colliersville  Plant,  Oswego  County,  New  York. 

Low  Head  Plants.  Low  head  turbines  are  usually  located  in  open  flumes,  with 
vertical  or  horizontal  shafts.  With  the  vertical  shaft,  frequently  several  turbines  are 
connected,  by  gearing,  to  one  horizontal  shaft.  With  this  arrangement,  special 
precaution  must  be  taken  to  exclude  moisture  from  the  generating  room. 

Fig.  i  shows  the  power  plant  of  the  Winnipeg  Electric  Railway  Company,  which 
utilizes  water  from  the  Winnipeg  River,  some  65  miles  from  the  city  of  Winnipeg, 
and  transmits  the  power  at  60,000  volts.1  A  channel  had  to  be  cut  to  the  Upper 
River  near  the  Otter  Falls,  120  feet  wide,  with  a  clear  depth  of  8  feet  at  normal  low 
water;  the  channel  is  8  miles  long  with  a  drop  of  5  feet  to  the  mile,  thus  giving  a  head 
of  40  feet.  The  units  are  McCormick  turbines  coupled  to  looo-K.W.  generators, 
making  200  R.P.M.,  and  are  equipped  with  Lombard  governors. 

It  will  be  noticed  that  two  pairs  of  turbines  with  two  draft  tubes  are  located  in 
one  casing,  which  is  an  extension  of  the  penstock.  The  gates  to  the  penstock  are 


1  Winnipeg,  Manitoba,  6o,ooo-VoIt  Hydro-electric   Plant,  by  V.  D.  Moody.     Electrical  World,  June  33, 


1906. 


POWER   PLANT.  91 

provided    with    by-pass    or    relief   valves,    to    facilitate  the   operation  of  the  main 
gate. 

Fig.  2  gives  the  power  house  cross  section  of  the  Albany  Power  and  Manufacturing 
Company,  located  on  Big  Shoals  on  the  Muckafoonee  River,  about  one  mile  below 
the  city  of  Albany,  Ga.1  For  utilizing  the  water,  a  dam  360  feet  long  and  20  feet 
high,  and  a  spillway  150  feet  long,  have  been  erected.  The  turbines  are  of  the  hori- 
zontal, radial,  inward  flow  type,  made  by  the  S.  Morgan  Smith  Company.  Each 
unit  comprises  four  wheels,  33  inches  in  diameter,  mounted  in  a  cast-iron  housing. 


•f«v  £H-*- — ^,^%,^-r^,^-.-.    "Tr^rt^rr'^r'j'-VJ'jrrrrJL^'^ 


FIG.  5. — Cross  Section  of  Colliersville  Plant,  Oswego  County,  New  York. 

The  discharge  through' each  pair  of  turbines  passes  through  a  draft  tube  7  feet  9  inches 
in  diameter,  made  of  one-quarter-inch  steel  plate.  The  head  on  the  turbines  is 
23  feet,  and  each  unit  is  capable  of  developing  900  HP.  at  full  gate.  They  are 
controlled  by  Lombard  governors,  and  connected  to  5OO-K.W.  generators. 

Medium  Head  Plants.  Medium  head  plants  are  usually  equipped  with  Francis 
turbines  of  the  horizontal  or  vertical  type.  When  the  horizontal  type  is  chosen,  there 
is  usually  only  one  wheel  mounted  on  the  shaft  coupled  to  the  generator,  and  supplied 
by  a  closed  penstock.  The  unit  must  be  set  above  ground  water.  With  the  adoption 

1  Hydro-electric  Plant  at  Albany,  Ga.,  by  R.  W.  Hutchinson,  Jr.     Electrical  World,  June  16,  1906. 


92 


HYDROELECTRIC    DEVELOPMENTS    AND   ENGINEERING. 


FIG.  6. — Map  of  the  Shawinigan  Power  Plant,  showing  Arrangement  of  Headrace  and 

Power  House. 


FIG.  7. — Cross  Section  of  McCall  Ferry  Power  House. 


POWER  PLANT.  93 

of  the  vertical  shaft  turbine,  in  almost  all  cases,  there  is  more  than  one  wheel  mounted 
on  the  shaft,  and  they  are  located  in  an  inclosed  wheel  pit,  or  else  in  a  steel  or  iron 
casing.  The  intake  and  draft  tubes  to  and  from  the  wheel  pit  must  be  smooth, 
particularly  when  made  of  concrete.  All  intakes  must  be  provided  with  vent 
pipes. 

Fig.  7  shows  the  general  arrangement  of  the  turbine,  generating  and  transformer 
rooms  of  the  McCall  Ferry  Power  Company's  plant.  The  plant  is  located  on  the 
Susquehanna  River,  about  25  miles  from  Chesapeake  Bay,  and  is  designed  for  a 
normal  capacity  of  100,000  HP.,  half  of  which  at  present  is  being  installed.  The 
dam  is  75  feet  high  and  2500  feet  long.  The  turbines,  furnished  by  the  I.  P.  Morris 
Company,  are  of  the  inward  and  flow  Francis  type,  mounted  in  pairs  on  a  single 
shaft.  At  a  speed  of  94  R.P.M.,  a  head  of  53  feet,  and  with  a  gate  opening  of  80 
per  cent,  they  are  capable  of  developing  13,500  HP.  The  turbines  are  connected 
to  7500-K.W.,  25-cycle  generators. 

The  location  of  the  power  house  in  relation  to  the  forebay  and  dam  is  shown  in 
Fig.  8.  The  building  stands  at  an  angle  of  42  degrees  with  the  face  of  the  main  dam.1 
It  comprises  a  screen  and  gatehouse,  generating  and  transformer  room.  At  one 
end  is  a  chute  for  ice  and  other  floating  material  which  may  collect  in  the  forebay. 
The  whole  building  is  built  of  concrete.  The  intake  conduit  for  one  main  unit  is 
comprised  of  three  openings,  6  feet  wide  and  16  feet  high.  Eight  feet  back  from  the 
gates,  they  merge  into  one,  which  is  15  feet  wide  and  for  a  short  distance  13  feet  high, 
and  expanding,  as  the  conduit  forms  the  turbine  chamber,  to  a  height  of  33  feet. 
There  are  two  draft  tubes,  one  leading  from  each  wheel  of  the  unit,  and  are  separated 
by  a  vertical  wall;  the  discharge  outlet  into  the  tailrace  of  each  unit  is  composed  of 
two  passages,  each  13  feet  wide  and  15  feet  high.  This  arrangement  of  the  draft 
tubes,  since  they  are  constructed  of  solid  concrete,  necessitated  very  complicated  form 
work,  especially  as  it  was  necessary  to  have  easily  curving  surfaces,  which  would 
offer  little  or  no  resistance  to  the  flow  of  water.  The  gates  closing  the  intake  conduits 
are  16  feet  high  and  6  feet  wide,  and  are  raised  and  lowered  by  a  1 5-ton  crane.  To 
facilitate  the  operation  of  the  gates,  they  are  provided  with  auxiliary  gates  which  are 
operated  by  the  crane.  In  front  of  the  gates  are  screens,  which  are  built  up  in  panels, 
10  feet  wide,  n  feet  high,  and  4  tiers  to  each  unit.  They  are  handled  by  the  overhead 
crane.  The  draft  tubes  are  provided  with  grooves  for  stop-logs. 

The  Niagara  Falls  power  plants  are  medium  head  plants,  but  of  an  entirely 
different  design  from  the  McCall  Ferry  Company's  plant.  Four  of  these  plants  have 
adopted  the  vertical  shaft  turbine  located  in  a  pit.  The  arrangements  vary  somewhat, 
especially  in  the  tailrace  end.  Power  House  No.  i  of  the  Niagara  Falls  Power  Com- 
pany, equipped  in  1895  witn  5ooo-HP.  units,  had  no  draft  tubes;  in  the  later  plants, 
both  on  the  American  and  Canadian  sides,  the  turbines  are  equipped  with  draft  tubes 
of  different  design,  as  is  shown  in  Figs.  9  and  10.  By  eliminating  the  draft  tube  in  the 
first  plant,  700  HP.  was  lost  for  each  of  the  ten  units. 

It  will  be  noticed  in  Fig.  n,  representing  the  arrangement  of  the  turbines  of  plant 
No.  2  of  the  Niagara  Falls  Power  Company,  that  the  draft  tube  is  divided,  and  the 

1  The  Engineering  Record,  Sept.  21,  1907. 


94  HYDROELECTRIC    DEVELOPMENTS   AND   ENGINEERING. 


A      a. 


N 


n 


MHO 


POWER  PLANT. 


95 


FIG.  9. — Arrangement  of  Turbines,  Niagara  Falls  Power  Company,  Plant  2. 


96 


HYDROELECTRIC   DEVELOPMENTS    AND    ENGINEERING. 


r 


. 
_     tfK,'  _   1.     -  IS'IO-     -  f-      -       ^'2' "5 

FIG.  10. — Cross  Section  of  Power  Plant  of  the  Toronto  and  Niagara  Power  Company. 


POWER  PLANT. 


97 


FIG.  ii. — Plan  of  Headworks  of  the  Toronto  and  Niagara  Power  Company. 


FIG.  12. — Cross  Section  of  Kern  River  Plant  No.  i. 


98  HYDROELECTRIC    DEVELOPMENTS   AND   ENGINEERING. 

branches  run  down  the  sides  of  the  tailrace  tunnel.  In  Fig.  12,  showing  the  arrange- 
ment of  the  turbines  of  the  Toronto  and  Niagara  Power  Company,  it  will  be  noticed 
that  there  are  two  tailrace  tunnels,  and  the  draft  tubes  discharge  into  the  tailrace 
from  underneath.  Half  of  the  turbines  discharge  into  the  right-hand  tunnel,  and 
half  into  the  left-hand. 

The  turbines  operate,  under  normal  conditions,  under  a  head  of  145  feet.  As 
the  generators  are  located  some  feet  above  the  headrace  or  forebay,  it  will  be  readily 
seen  that  long  shafts  are  necessary.  These  shafts  are  divided  into  three  sections 
carried  on  one  adjustable  thrust  bearing,  and  guided  by  two  side  bearings.  In  the 
American  plant,  the  bearings  are  supported  on  structural  steel  galleries,  while  in  the 
Toronto  and  Niagara  Company,  they  are  supported  on  heavy  concrete  arched 
floors. 

The  vertical  penstocks  leading  to  the  turbines  are  well  anchored  at  the  upper  and 
lower  end.  To  allow  for  expansion,  slip  joints  are  provided  at  the  upper  end.  In 
digging  the  turbine  pits  at  Niagara  Falls,  many  difficulties  were  experienced;  some  of 
them  have  a  depth  of  175  feet,  a  width  of  only  17  to  22  feet,  and  run  the  entire  length 
of  the  power  houses,  which  are  400  to  500  feet  long.  Much  of  the  work  was  done  in 
rock  of  different  formation,  which  was  exposed  as  the  work  progressed.  All  the 
plants  are  well  provided  with  screens  and  ice  racks,  in  separate  houses.  To  prevent 
floating  material  from  entering  the  forebay  and  screen  rooms,  the  curtain  walls  are 
extended  some  several  feet  into  the  water. 

High  Head  Plants.  High  head  plants  usually  have  a  simple  arrangement  of 
turbines,  but,  on  the  other  hand,  they  have  a  more  complicated  arrangement  of 
penstock  and  regulating  devices.  It  is  but  natural  that  high  head  plants  are  located 
away  from  center  of  current  distribution,  therefore  a  large  electrical  equipment  is 
connected  to  the  plant.  As  the  ground  is  cheap  in  such  localities,  it  would  be  an 
unwise  policy  to  crowd  the  generating  room.  Ample  space  must  be  allowed,  particu- 
larly for  the  regulating  devices. 

One  of  the  most  prominent  high  head  plants  in  the  United  States  is  the  Kern 
River  Plant  No.  I,  of  the  Edison  Company,  Los  Angeles.  It  utilizes  the  water  of  the 
Kern  River,  and  has  a  rated  capacity  of  20,000  K.W.  The  current  at  60,000  volts 
is  transmitted  117  miles  to  Los  Angeles  and  other  towns. 

To  harness  the  water  of  the  Kern  River,  a  dam  203  feet  long,  20  feet  above  the 
river  level,  was  constructed.1  The  water  is  first  led  through  19  tunnels,  aggregating 
a  length  of  42,910  feet;  then  through  timber  flumes  1520  feet  long,  then  through  a 
reinforced  concrete  conduit  503  feet  long,  where  it  enters  a  forebay.  From  the  forebay 
leads  a  penstock  1697  feet  long,  to  the  power  house.  Contrary  to  the  usual  practice 
of  laying  the  conduit  on  the  mountain  slope,  this  penstock  is  run  through  a  tunnel. 
Throughout  the  course,  there  are  several  horizontal  curves  and  vertical  bends, 
amounting  to  40  and  45  degrees.  The  penstock  in  the  tunnel  has  a  diameter  of 
7.5  feet,  and  near  the  power  house  the  diameter  is  reduced  to  5.25  feet. 2 

1  The  Kern  River  Power  No.  i,  by  C.  W.  Whitney.     The  Engineering  Record,   Aug.  10,  17,  24,  31, 
1907. 

2  For  details  on  construction,  see  chapter  on  Penstocks. 


POWER   PLANT. 


99 


As  seen  in  the  plan  (Figs.  12  and  13),  the  branches  from  the  main  penstocks 
lead  beneath  the  switching  room  to  the  impulse  wheels.  Two  Allis-Chalmers  impulse 
wheels  drive  one  5ooo-K.W.  generator,  and  are  mounted  on  the  overhanging  shaft 
of  the  generator.  Each  wheel  is  9  feet  8  inches  in  diameter,  and  has  18  buckets. 
The  guaranteed  output  of  one  pair  of  wheels  is  10,750  H.P.  at  150  R.P.M.  The  nozzle 
is  adjustable,  so  that  the  stream  can  be  deflected  from  the  buckets.  It  is  provided 
at  the  stationary  end  with  a  ball  and  socket  joint  heavily  bolted  down  to  the  con- 
crete foundation.  This  swiveling  head  has  to  take  up  the  full  pressure  of  375,000 
pounds.  The  regulation  of  the  wheels  is  effected  by  a  governor,  which  deflects  the 
jets  of  the  two  nozzles.  The  needles  are  adjusted  by  hand,  and  are  usually  set  so 
that  maximum  size  of  jet  which  will  be  sufficient  to  develop  the  maximum  peak 


FIG.  13. — Plan  of  Kern  River  Plant  No.  i. 

loads  expected  for  that  period  of  the  needle  setting;  in  other  words,  there  is  always 
a  maximum  amount  of  water  leaving  the  nozzles.  The  governor  adjusts  the  deflect- 
ing nozzles  in  such  a  way  that  only  as  much  water  is  directed  upon  the  buckets  as  is 
needed  for  the  load  for  the  time  being.  The  balance  discharges  below  the  buckets 
into  the  tailrace.  Each  jet  has  a  maximum  diameter  of  7!  inches  and  leaves  the 
nozzle  tip  at  a  velocity  exceeding  225  feet  per  second.  It  was  necessary  to  provide 
means  for  receiving  this  tremendous  power  and  deflecting  the  jet  into  the  tailrace  in 
such  a  way  that  its  impact  would  not  be  detrimental  to  the  structure  against  which 
it  is  directed. 

The  arrangement  designed,  consists  of  a  pair  of  heavy  deflector  plates  by  which 
the  jet  is  diverted.  These  plates  are  curved,  their  design  being  such  as  to  turn  the 
water  through  two  right  angles  before  it  is  allowed  to  pass  into  the  tailrace,  thus  reduc- 
ing the  force  of  the  water  so  that  it  can  do  no  damage.  The  upper  of  these  plates 


IOO 


HYDROELECTRIC    DEVELOPMENTS    AND    ENGINEERING. 


MM* 

dfff 

1    'IronScnen 
'          -TimberScrtm 


consists  of  a  channel,  heavily  ribbed  and  bolted  to  the  concrete  foundation.  The 
channel  at  its  upper  end  is  slightly  more  inclined  than  the  deflected  jet.  Thus,  the 
jet  strikes  the  bottom  of  the  channel  at  a  small  angle,  and  therefore  tends  to  spread 
and  fill  the  section.  The  channel  gradually  widens,  and  the  jet  is  consequently 
offered  a  larger  resistance  area.  The  lower  part  of  the  channel  is  curved,  and  at  its 

end  the  jet  discharges  almost  perpen- 
dicularly downward.  The  bottom  plate 
is  S-shaped,  its  upper  end  being  flush 
with  the  bottom  of  the  wheel  pit,  the 
lower  end  being  practically  level.  The 
jet  strikes  the  bottom  plate  almost  in  the 
turn  of  the  S  and  under  a  small  angle. 
Thus  the  jet  is  again  forced  to  spread  and 
follow  the  base  of  the  bottom  plate.  The 
deflectors  are  lined  with  movable  steel 
plates  wherever  the  surfaces  are  exposed 
to  the  flow  of  the  deflected  jet,  and  held 
in  position  by  lag  screws.  The  plates  are 
7  feet  wide,  and  the  lower  one  projects  out 
into  the  tailrace  8  feet.  The  wheel  races 
are  lined  with  steel  on  both  sides,  and 
fitted  with  steel  back  plates  just  back  of 
the  nozzle  tips,  to  keep  the  splash  water 
out  of  the  shaft  alley. 

The  tailrace  is  29  feet  wide  and  ex- 
tends the  length  of  the  power  house.  It 
is  fitted  with  two  2 5 -foot  steel  plate  weirs; 
the  lower  weir  at  the  end  of  the  tailrace 
being  4  feet  below  the  level  of  the  upper, 
which  has  its  crest  13  feet  6  inches  below 
the  line  of  the  nozzles. 

The  penstock  branches  enter  the  power 
house  at  the  south  side,  and  after  passing 
across  the  transformer  rooms,  and  before 
joining  the  nozzle  bases,  connect  to  28-inch 
These   valves  are  of  a  special  design,  and    are  separately 


SwHcH 
"Board 


FIG.  14. — Power  Plant  of  Snoqualmie  Falls. 
Power  Development. 


cast-steel  gate  valves, 
operated  from  the  control  switchboard  by  a  I.2-H.P.,  i2o-volt  Allis-Chalmers  motor. 
These  motors  are  mounted  vertically  and  operate  at  460  R.P.M.  It  requires  7$ 
minutes  to  open  or  close  a  valve  by  means  of  the  motor.  All  of  the  gate  valves  are 
equipped  with  4-inch  by-passes.  In  the  machine  room  of  the  power  house  is 
installed  a  Dibble  reservoir  gate  equipped  with  an  indicating  dial  and  a  registering 
chart,  for  measuring  the  water  in  the  forebay. 

A  very  unique  arrangement  of  a  high  head  power  plant  layout  is  that  of  the 
Snoqualmie  Falls  and  White  River  Power  Transmission  Plant  in  Washington  (see 


102  HYDROELECTRIC  DEVELOPMENTS  AND  ENGINEERING. 

Fig.  14).  A  shaft  of  rectangular  section,  27  feet  long  and  10  feet  wide,  was  sunk 
in  the  river  bed  about  300  feet  above  the  Snoqualmie  Falls.  This  shaft  reaches  a 
depth  of  270  feet,  or  the  level  of  the  river  below  the  falls,  and  connects  with  a  tunnel 
24  feet  high  and  12  feet  wide,  having  a  slope  of  two  feet,  utilized  as  a  tailrace.1  The 
underground  power  station  begins  at  the  bottom  of  this  shaft  and  is  30  feet  high, 
40  feet  wide,  and  about  200  feet  long.  The  tunnel,  power  house  and  shaft  are 
lighted  by  incandescent  lamps;  the  natural  draft  through  the  tailrace  and  up  the 
shaft  provides  good  ventilation.  The  temperature  remains  constant  at  55°  F., 
and  the  generating  room  is  perfectly  dry. 

There  are  three  vertical  shafts  leading  to  the  power  house;  one  for  elevator,  and 
cables  conducting  the  current  to  the  distributing  station  on  the  shore;  the  others  for 
penstocks.  The  elevator  shaft,  10  feet  long  and  8  feet  wide,  is  lined  with  steel  casing 
backed  with  concrete. 

The  penstock  has  a  diameter  of  7.5  feet,  and  is  built  of  steel  plate  sections,  having 
a  thickness  of  0.5  inch  on  the  top  and  one  inch  on  the  bottom.  Here  it  is  connected 
to  a  horizontal  chamber,  10  feet  in  diameter  at  the  penstock  junction  and  8  feet  in 
diameter  at  the  opposite  end.  From  this  chamber,  four  4-foot  branches  lead  to  the 
turbines,  which  are  of  the  Doble  impulse  wheel  type,  having  a  capacity  of  2500  HP., 
making  300  R.P.M.,  and  connected  to  I5OO-K.W.,  icoo-volt,  3-phase  Westing- 
house  generators.  Each  unit  is  composed  of  6  impulse  wheels  mounted  on  a 
common  shaft,  each  wheel  having  two  jets. 

EXCAVATION   AND    FOUNDATION. 

Selection  of  Site.  In  connection  with  the  head  and  tail  race,  and  the  selection  of 
the  site  for  the  power  house,  the  character  of  the  soil  must  be  considered.  It  frequently 
happens  that  forced  choice  for  the  site  of  the  power  house  of  a  plant  is  on  unsuitable 
soil.  To  overcome  this  difficulty  there  are  two  ways:  either  change  the  location  of 
the  site,  or  strengthen  the  soil.  It  is  therefore  essential,  before  drawing  up  plans  of  the 
general  arrangement,  that  accurate  information  is  obtained  regarding  the  bearing 
power  of  the  soil.  This  is  secured  by  sinking  test  holes.  If  the  soil  is  of  an  unknown 
character,  test  loads  must  be  applied. 

Test  Holes.  Test  holes  must  be  sunk  in  alluvial  soil,  or  made  land,  to  secure 
accurate  knowledge  of  the  underlying  strata.  Frequently,  in  the  sinking  of  test 
holes,  rocks  are  encountered;  this  indication  must  not  always  be  taken  for  strata  of 
rock.  To  ascertain  that  rock  does  not  exist,  holes,  short  distances  apart,  must  be 
sunk,  so  that  an  accurate  plot  of  the  soil  is  obtained.  These  holes  are  usually  25  to 
50  feet  apart.  When  the  magnitude  of  the  project  does  not  warrant  the  use  of  well 
or  core  drilling  machines,  test  holes  can  be  put  down  by  driving  iron  pipe;  a  small 
and  large  one  can  be  used,  the  large  one  acting  as  a  shell  for  the  smaller,  to  prevent 
the  hole  from  caving  in.  A  core  can  be  secured  by  leaving  the  lower  end  of  the  small 
pipe  open,  and  working  without  the  use  of  water.  An  easy  method  is  to  force  a 

1   Electrical  Review,  June  18,  1904. 


POWER   PLANT. 


stream  of  water  down  the  small  pipe,  which,  returning  to  the  surface  through  the  large 
one,  brings  up  specimens  of  the  soil.  With  a  scheme  of  this  kind,  holes  may  be 
driven  50  feet  or  more,  depending  on  the  character  of  the  soil. 

Character  of  the  Soil.  When  rock  is  present  within  moderate  depth,  the  founda- 
tion must  be  carried  down  to  same.  The  surface  of  the  rock  must  be  leveled  and 
cleaned  in  order  to  give  a  good  bearing.  The  bearing  value  of  rock  varies  within 
wide  limits,  from  10  to  200  tons  per  square  foot  and  even  higher. 

A  clean  sharp  sand  makes  an  ideal  bearing  soil,  and  is  easy  to  excavate;  in  addition, 
it  may  be  utilized  in  the  making  of  mortar  and  concrete,  which  means  considerable 
in  saving  and  expense.  Quicksand,  either  wet  or  dry,  if  in  thin  layers,  should  be 
removed  entirely;  where  it  is  underlaid  with  a  firm  strata,  it  can  be  confined  by 
means  of  a  concrete  coffer  dam,  and  the  foundations  can  then  be  floated  on  same. 
The  footing  or  mat  covers  the  entire  area  within  the  coffer  dam.  In  soft  or  alluvial 
soil,  piling  is  necessary  for  heavy  foundations.  As  a  general  rule,  the  firmness  of  the 
soil  increases  with  the  depth;  there  are  exceptions,  however.  In  Chicago,  the  firm 
upper  layer  of  soil,  from  10  to  20  feet  in  thickness,  is  underlaid  by  a  soft  clay  stratum 
about  70  feet  thick,  under  which  is  a  stratum  of  firm  clay.  Similar  conditions  have 
been  noticed  in  different  parts  of  the  country.  Clay  varies  greatly  in  consistency, 
varying  from  fluid  to  hard  shale;  the  latter,  when  exposed,  will  disintegrate.  It  varies 
greatly  according  to  the  opportunity  for  absorbing  or  losing  water,  and  because  of 
this,  it  is  very  troublesome.  To  make  a  good  foundation,  clay,  sand  and  stone  are 
spread  on  it,  and  then  well  rammed  down.  The  stones  should  be  small  enough  to 
permit  their  being  handled  by  one  man. 

As  a  general  rule,  hydraulic  plants  are  located  in  rocky,  mountainous  districts; 
and  as  the  plants  are  frequently  located  on  the  mountain  slope,  a  simple  and  efficient 
way  is  to  blast  the  rock  in  steps. 

Bearing  Power  of  Soil.  For  the  bearing  power  of  soils,  the  values  in  the  following 
table  are  from  Baker's  "  Treatise  on  Masonry  Construction": 


TABLE    I. —  SAFE    BEARING    POWER    OF    SOILS. 


Kind  of  material. 

Safe  bearing  power  in 
tons  per  square  foot. 

Minimum. 

Maximum. 

Rock  —  the  hardest  —  in  thick  layers  in  native  bed.. 
Rock,  equal  to  best  ashlar  masonry  

200 

25 
IS 

5 
4 

2 

8 

4 

2 

o-S 

3° 
20 

10 

6 

4 
10 
6 

4 

I 

Rock,  equal  to  best  brick  masonry    

Rock,  equal  to  poor  brick  masonry  

Clay,  in  thick  beds,  always  dry  

Clay,  in  thick  beds,  moderately  dry  

Gravel  and  coarse  sand,  well  cemented  

Sand,  compact  and  well  cemented   

Sand,  clean,  dry  

Ouicksand,  alluvial  soils,  etc  

104 


HYDROELECTRIC    DEVELOPMENTS   AND   ENGINEERING. 


Weight  of  Masonry.  For  the  total  bearing  stress  of  a  foundation  on  the  soil,  the 
weight  of  the  foundation  itself  must  be  included.  For  use  in  this  connection,  Table  II, 
taken  from  the  same  authority,  gives  the  weights  of  various  types  of  masonry : 


TABLE    II. —  WEIGHT    OF    MASONRY. 


Kind  of  masonry. 

Weight  in  pounds  per 
cubic  foot. 

Brickwork,  pressed  brick,  thin  joints  ...    . 

1AC 

Brickwork,  ordinary  quality  

T2C 

Brickwork,  soft  brick,  thick  joints  

l*5 

Concrete,  i  cement,  3  sand,  and  6  broken  stone  

I/1O 

Granite,   6  per  cent  more  than  the  corresponding 
limestone  

Limestone,  ashlar,  largest  blocks  and  thinnest  joints. 
Limestone,  ashlar,   12  to  zo-inch  courses  and  f  to 
}-inch  joints  .    .        ... 

160 

TCC 

Limestone,  squared  stone  

148 

Limestone,  rubble,  best  

14.2 

Limestone,  rubble,  rough  

1*6 

Mortar,  i  Rosendale  cement  and  2  sand  

116 

Mortar,  common  lime,  dried  

IOO 

Sandstone,   14  per  cent  less  than  the  corresponding 
limestone  ... 

Piling.  There  are  different  kinds  of  piles,  such  as  wooden,  sand  and  concrete. 
Wooden  piles  are  used  in  two  ways:  they  are  driven  down  in  soft  soil  to  compact  it, 
in  which  case  the  bearing  power  depends  entirely  upon  friction.  In  other  cases,  the 
piles  are  driven  to  rock  or  solid  strata,  in  which  case  they  act  as  a  column.  Wooden 
piles  must  be  cut  off  below  the  permanent  ground  water  line  to  prevent  the  caps  from 
decay,  and  on  top  of  wooden  piles  is  spread  a  concrete  cap. 

Sand  piles  are  used  for  strengthening  the  soil,  by  driving  wooden  piles  or  hollow 
sheet  steel  tubes  down,  then  withdrawing  them;  the  hole  is  then  rilled  with  sand. 
These  piles  are  usually  spaced  close  together,  and  do  not  act  like  wooden  piles;  the 
whole  soil  is  made  compact. 

In  the  last  few  years,  much  use  has  been  made  of  concrete  piles,  both  plain  and 
reinforced  with  steel.  Two  general  methods  are  employed:  in  one,  the  piles  are 
molded,  then  driven;  in  the  other,  the  mold  is  driven  with  a  removable  core,  the 
concrete  being  placed  after  the  core  has  been  removed.  There  are  several  other 
schemes  of  concrete  piling,  but  the  principles  do  not  differ  from  those  mentioned. 
The  many  advantages  of  concrete  piling  are  obvious,  such  as,  they  cannot  decay,  and 
for  this  reason  they  can  be  left  as  high  as  desired;  and  more  economical  foundations 
secured,  owing  to  the  fact  that  the  ground  water  line  does  not  signify  the  point  for 
the  cap,  as  it  does  with  wooden  piles.  The  friction  and  bearing  power  is  higher  than 
that  of  wood.  In  addition,  the  diameter  of  a  concrete  pile  can  be  varied  at  will, 
while  the  diameter  of  a  wooden  pile  rarely  exceeds  14  inches.  For  this  reason  fewer 
concrete  piles  are  necessary  for  supporting  a  given  load.  They  are,  in  a  way,  down- 
ward projections  of  the  monolithic  mass  of  the  foundations. 


POWER  PLANT. 


105 


Corrvqafecf  Reinforced  Concrete  Piling  Wood 

FIG.  16. — Comparison  of  Foundations  using  Wooden  and  Concrete  Piles. 

Test  of  Piles.  The  difference  in  bearing  power  between  a  conical  and  a  cylin- 
drical pile  was  shown  by  an  experiment,  tried  on  some  work  at  the  United  States 
Naval  Academy  at  Annapolis,  Md.  A  Raymond  pile  core,  tapering  from  6  inches 
at  the  point  to  20  inches  at  the  butt,  was  driven  19  feet,  until  the  penetration,  under 
two  blows  from  a  2100- pound  hammer  falling  20  feet,  was  seven-eighths  of  an  inch. 
A  wooden  pile  9^  inches  at  the  point  and  n  inches  at  the  butt,  and  of  the  same 


106  HYDROELECTRIC    DEVELOPMENTS   AND    ENGINEERING. 

length  as  the  conical  pile,  had  a  penetration  of  5  finches  under  two  blows  of  the  same 
hammer  falling  20  feet.  A  ly^-foot  test  pile  having  the  same  dimensions  as  the 
concrete  pile  above  mentioned,  and  having  a  penetration  of  i  inch  under  twenty 
blows  of  a  steam  hammer,  was  loaded  with  41  tons.  Levels  were  taken  during  the 
loading,  and  at  intervals  for  one  month.  At  the  end  of  the  month  the  total  settle- 
ment was  0.007  foot,  or  three-thirty-seconds  inch. 

Concrete  Mat  Construction.  Concrete  mat  construction  is  frequently  used  with 
earth  filling,  also  on  soft  ground  where  pile  driving  has  been  done.  To  guard  against 
unequal  settlement,  it  is  preferable  to  extend  the  mat  Under  the  entire  building.  The 
thickness  of  the  mat  varies  with  the  load  to  be  applied,  and  may  be  kept  down  by 
reinforcing  same,  preferably  with  old  rails.  The  mixture  for  the  concrete  in  the  latter 
case  is  i  :  3  :  6;  if  a  more  expensive  mixture  is  desired,  use  i  :  2\  :  5.  When  plain 
concrete  slabs  are  used,  rubble  concrete  may  be  employed  up  to  a  few  inches  of  the 
floor  line. 

Foundations.  In  determining  the  size  of  foundations,  the  weights  of  the  machinery 
must  be  secured  from  the  manufacturer.  In  most  cases,  the  sizes  are  indicated  on  the 
blue  prints;  this,  however,  is  not  sufficient,  as  one  case  cannot  serve  for  all;  as  all 
depends  on  the  character  of  the  soil.  In  the  case  of  turbines,  the  weight  of  water 
must  be  figured  in  with  the  weight  of  the  machines. 

Foundations  must  always  be  made  of  concrete,  i  :  2\  :  5  for  the  smaller  type, 
and  i  :  3  :  6  for  larger  foundations.  As  will  be  seen  in  the  chapter  on  buildings,  the 
substructure  of  an  hydraulic  plant  is  usually  a  monolithic  mass  of  concrete.  The 
forms  for  the  foundation  should  be  so  designed  that  they  can  be  used  over  and  over 
again,  where  there  are  a  number  of  isolated  foundations.  This  is  also  true  in  the 
case  of  core  forms  in  wheel  pits,  draft  tubes,  etc.,  provided  there  will  be  no  serious 
interruption  of  the  work.  The  forms  must  not  be  removed  until  the  concrete  is 
thoroughly  set,  otherwise  the  concrete  will  assume  a  different  shape. 

For  locating  anchor  bolts,  templates  must  be  constructed.  They  are  made  of 
planking  and  thoroughly  braced  with  diagonal  bracing,  otherwise  the  template  will 
warp  out  of  shape,  and  throw  out  the  location  of  the  anchor  bolts.  The  drawings 
should  not  only  contain  the  elevations  of  foundations,  bolts,  etc.,  but  also  dimensions 
to  simplify  construction  of  same. 

Anchor  Bolts.  The  anchor  bolts  for  machinery  are  preferably  made  removable, 
particularly  with  large  machinery.  Under  ordinary  conditions,  they  need  not  project 
into  the  foundations  more  than  18  or  24  inches.  They  are  provided  on  the  bottom 
end  with  a  cast-iron  washer,  6  to  12  inches  square.  The  6-inch  washer  is  sufficient 
for  bolts  i  to  i^  inches  in  diameter.  They  are  inclosed,  between  the  washer  and 
foundation  (with  no  grouting),  in  a  pipe,  with  a  diameter  about  one  inch  larger  than 
the  bolt.  The  bolts  are  threaded  at  both  ends  to  permit  adjustment.  All  bolts, 
washers  and  pipes  should  preferably  be  of  standard  size,  to  minimize  expense  in 
draughting  department,  shop  and  field. 

Grouting.  After  the  machinery  has  been  properly  set  in  place,  and  anchored 
down,  grout  must  be  poured  in  to  establish  a  final  setting  for  the  bed  plate.  There 
must  be  an  allowance  in  the  foundation  from  one  inch  to  two  inches;  and  even  in 


POWER  PLANT. 


107 


small  foundations  such  as  for  pumps,  etc.,  it  must  not  be  less  than  three-fourths 
of  an  inch  thick.  The  grouting  itself  is  a  thin,  rich  mixture  of  cement  mortar  with 
little  or  no  sand,  in  order  to  fill  up  all  spaces  between  the  bed  plate  and  foundation 
and  around  the  anchor  bolts. 

SUPERSTRUCTURE. 

Architectural  Features.  Rapid  progress  has  been  made  in  the  last  few  years  in  the 
design  of  hydraulic  plants  and  their  substations.  The  designs  show  a  more  harmo- 
nious agreement  between  engineer  and  architect;  this, however,  varies  with  the  different 
countries;  some  lay  much  stress  upon  the  artistic  appearance,  while  others  confine 
their  attention  solely  to  utilitarian  objects,  disregarding  entirely  the  architectural 
features.  Necessity  requires  only  a  building  of  sufficient  support,  to  shelter  and 


FIG.  i. — Entrance  Hall  of  Plant  No.  2,  of  the  Niagara  Falls  Power  Company. 


protect  the  machinery  and  those  who  operate  it,  and  must  be  of  durable  construction. 
An  ornamental  building  will  not  increase  the  efficiency  of  the  machinery;  it  increases 
the  fixed  charges.     But,  at  the  same  time,  it  is  required  from  an  aesthetic  point  of 
view,  and  will,  no  doubt,  have  certain  effect  upon  the  moral  of  the  operating  force,  ' 
whose  efficiency  will  be  increased  thereby. 

The  ultimate  aim  in  the  design  of  an  hydraulic  plant  is,  to  generate  electricity 


108  HYDROELECTRIC    DEVELOPMENTS   AND   ENGINEERING. 

upon  a  commercial  and  economical  basis.  As  a  rule,  hydraulic  plants  are  located 
away  from  centers  of  population,  consequently  the  architectural  features  are 
neglected,  as  is  evidenced  by  many  of  the  soap-box-like  structures  in  America  and 
England.  It  seems  strange  that  the  hydraulic  and  electrical  engineers  of  these 
countries  pay  little  or  no  attention  to  the  architectural  features  of  buildings. 

There  are,  however,  a  few  examples  which  show  the  excellent  harmony  between 
the  engineer  and  architect.  Some  of  them  are  found  at  Niagara  Falls,  for  example 
the  upper  works,  or  headrace  at  Dufferin  Islands,  of  the  Ontario  Power  Company, 
whose  power  house  is  located  in  the  Gorge.  It  might  be  of  interest  to  give  an  extract 
from  a  report  of  the  park  commissioners,  when  the  franchises  were  granted  to  the 
various  power  companies  on  the  Canadian  side  of  Niagara  Falls. 

"All  of  the  works  and  structures  connected  with  the  electrical  power  projects 
have  been  designed  with  the  object,  not  only  of  doing  the  least  possible  injury  to  scenic 
conditions,  but  the  commissioners  are  confident  in  the  belief,  that  when  the  several 
works  are  completed,  the  consensus  of  opinion,  by  the  vastly  increased  number  of 
visitors  that  are  expected  to  visit  the  park,  will  abundantly  sustain  them  in  their 
contention,  that  the  park  as  a  whole,  with  its  wealth  of  electrical  machinery,  will  then 
be  of  tenfold  greater  interest  to  the  great  majority  visiting  it." 

A  building  for  power-house  purposes  should  not  be  too  ornate,  as  is  frequently 
found  in  Europe.  Simplicity  of  design  and  harmonious  agreement  with  its  sur- 
roundings are  of  prime  importance.  The  machinery  must  be  well  arranged,  sufficient 
ventilation  and  an  abundance  of  light  provided. 

A  plant,  one  of  the  foremost  in  America,  not  only  regarding  the  equipment  and 
capacity,  but  also  from  the  architectural  point  of  view,  both  exterior  and  interior, 
is  that  of  the  Niagara  Falls  Power  Co.,  Figs.  2  and  3.  The  superstructure  is  of  rough 
faced  granite  blocks  with  a  slate  roof.  In  front  of  the  main  structure  is  the  screen 
house.  Both  structures  are  well  provided  with  windows  for  light  and  ventilation. 
The  building  is  tasteful  in  design  and  is  typical  for  its  purpose,  namely,  that  of  a 
power  plant.  The  interior  design  of  the  generating  room  is  in  keeping  with  the 
exterior,  while  the  entrance  hall  has  been  more  elaborately  treated  (see  Fig.  i).  The 
electric  illumination  of  the  entrance  is  in  perfect  harmony  with  the  architectural 
design.  What  has  been  done  in  main  hydraulic  plants  has  been  typified  in  sub- 
stations, as  seen  in  Fig.  4. 

In  Europe,  the  architectural  features,  from  an  American  point  of  view,  are 
exaggerated  in  the  extreme.  Fig.  5  represents  the  hydraulic  plant  of  the  city  of 
Stuttgart,  Germany.  The  style  is  that  of  the  fourteenth  century,  and  is  much  favored 
in  Continental  power  plant  practice.  The  approach  leading  from  the  street  to  the 
power  house  harmonizes  with  the  main  structure.  This  plant  is  equipped  with 
four  3OO-HP.  hydraulic  units,  and  a  small  storage  battery  of  300  ampere-hour 
capacity.  In  America  this  plant  is  considered  small,  and  in  all  probability  the 
architectural  features  would  be  neglected.  It  will  be  observed  that  much  money  is 
spent  for  architectural  purposes,  in  fancy  cornices  and  off-sets,  in  the  above  building. 
However,  it  is  not  necessary  to  secure  pleasing  architecture  in  such  a  manner;  contrast 
the  above  plant  with  that  of  Obermatt,  near  the  city  of  Lucerne,  Switzerland 


POWER  PLANT. 


109 


FIGS.  2  and  3. — Exterior  and  Interior  of  Plant  No.  2  of  the  Niagara  Falls  Power 

Company. 


FIG.  4.— Substation  of  Great  Northern  Power  Company,  Duluth,  Minnesota. 


(no) 


FIG.  5.— Municipal  Plant,  Stuttgart.  Germany. 


POWER  PLANT.  ill 

(Fig.  6).  Attention  is  called  to  the  novel  design  of  the  windows.  The  interior  of 
this  power  house  is  given  in  Fig.  7. 

A  German  plant  designed  entirely  on  modern  "  Secession  "  style  is  that  of  the 
power  plant  of  the  Urfttalsperre  at  Heimbach,  shown  in  Figs.  8  and  9.  The  entire 
design,  such  as  the  arrangement  and  design  of  the  pilasters,  roof  trusses,  windows 
and  switchboards,  is  patterned  on  the  same  line.  Special  attention  is  called  to  the 
design  of  the  windows  and  doors,  the  rear-end  wall  and  side-wing  towers.  The 
latter  may  be  taken  for  ornamental  bases  for  smokestacks.  While  individual  features, 
such  as  switchboards,  have  appeared  in  Continental  practice  for  years,  the  design, 
as  a  whole,  is  a  bold  one  in  power  plant  practice. 

Material.  In  the  construction  of  electric  plants,  it  is  essential  to  have  the  buildings 
as  fireproof  as  possible.  This  can  be  secured  by  using  concrete,  brick,  terra-cotta, 
or  steel.  The  material  adopted  depends  greatly  upon  the  locality  and  on  the  labor 
supply. 

In  some  countries  or  sections  of  countries,  skilled  labor  is  easily  obtainable;  in 
many  places  material  and  skilled  labor  have  to  be  carried  to  the  site.  For  buildings 
in  such  localities  concrete  and  steel  are  the  best;  with  a  few  skilled  foremen  and  pick- 
up labor,  such  buildings  can  be  easily  erected.  This  is  particularly  true  in  tropical 
countries  where  labor  is  difficult  to  secure.  In  countries  subject  to  earthquakes,  a 
framework  of  steel  covered  with  corrugated  iron  serves  admirably  well;  the  corrugated 
sheets  lapping  over  each  other  five  inches,  and  from  one  and  a  half  to  two  inches 
on  the  side.  In  some  cases  painted  corrugated  sheets  are  used,  owing  to  their 
cheapness  of  cost.  The  material  should  preferably  be  galvanized,  in  which  condition 
it  should  not  receive  a  coat  of  paint  until  it  is  exposed  to  the  weather  one  or  two 
years,  and  the  surface  has  become  slightly  oxidized. 

Walls.  The  interior  of  the  generating  and  switching  room  should  be  kept  as 
light  as  possible.  It  is  advisable  to  apply  a  smooth  surface  of  cement  plaster,  and 
whitewash  same.  A  more  pleasing  effect  will  be  secured  by  facing  the  walls  with 
enameled  tile  and  a  wainscoting  of  contrasting  color.  Pilasters  may  be  used  to 
break  up  the  monotony  of  a  smooth  surface,  and  conceal  steel  columns  of  the  crane 
runway.  The  tiling  of  the  walls  should  preferably  be  of  cream  color,  while  the 
wainscoting  and  ornamental  panels  of  olive-green.  However,  the  selection  of  the 
latter  color  is  governed  by  other  conditions,  particularly  that  of  the  floor. 

The  switching  room  should  be  separated  from  the  generating  room  by  a  parti- 
tion wall  of  fireproof  material.  Large  openings  should  be  left  in  this  wall,  particu- 
larly in  the  control  switchroom,  so  that  the  operators  can  have  an  unobstructed  view 
of  the  generating  room;  glass  partition  walls  serve  the  same  purpose,  and  have  the 
advantage  of  excluding  all  dust. 

Floors.  In  the  construction  of  floors,  non-combustible  material  must  be  employed. 
As  the  substructure  is,  in  most  cases,  built  of  concrete,  it  is  but  natural  that  the 
floors  should  be  of  concrete;  in  this  case,  they  must  have  a  granolithic  finish  of  dark 
color,  to  render  drips  of  oil  inconspicuous.  Some  authorities  dislike  concrete 
floors,  for  the  reason  that  such  floors  produce  grit  by  wear,  which  is  stirred  up  by 
walking  and  sweeping,  thereby  getting  into  the  bearings  and  other  parts  of  the 


112  HYDROELECTRIC    DEVELOPMENTS   AND   ENGINEERING. 


FIGS.  6  and  7.— Exterior  and  Interior  of  Obermatt  Plant,  Lucerne,  Switzerland. 


POWER  PLANT. 


FIGS.  8  and  9. — Exterior  and  Interior  of  Urfttalsperre  Plant  at  Heimbach,  Germany. 


114  HYDROELECTRIC    DEVELOPMENTS    AND   ENGINEERING. 

machinery.  Another  reason  is,  that  a  person  on  a  concrete  floor  coming  in  contact 
with  any  high-tension  wiring,  would  instantly  be  killed,  while  a  wooden  floor  would 
minimize  the  risk.  The  use  of  wood  in  power  plant  construction,  and  particularly 
in  floors,  is  obsolete;  the  principal  reason  being,  that  around  machinery,  there  is 
more  or  less  dripping  of  oil,  which  soaks  into  such  a  floor  and  shortly  gets  into  a 
very  inflammable  condition.  In  fact,  the  whole  trouble  of  some  power  plant  fires 
has  been  due  to  an  insignificant  blaze  of  the  wooden  flooring.  Probably,  the  best 
floor  finish  for  a  generating  room  is  tile  or  mosaic;  being  smooth,  it  is  easy  to  keep 
clean,  and  has  a  very  handsome  appearance. 

Penstock  connections  and  generator  leads  are  frequently  laid  in  trenches, 
curbed  and  covered  by  plates;  for  the  sake  of  appearance,  if  possible,  they  should 
run  lengthwise  or  transverse  to  the  building.  It  is  poor  engineering  to  have  the 


FIG.  10. — Municipal  Plant,  Geneva,  Switzerland. 

branches  of  the  penstock  embedded  in  the  concrete  floor,  and  it  is  still  worse  to  have 
flanges  of  same  project  above  the  floor. 

Roof.  The  cheapest  non-fireproof  roof  construction  is  boards  covered  with 
roofing  felt,  on  which  is  laid  a  pitch  and  gravel  roof.  This  type  of  roof  is  suitable 
for  slopes  ranging  from  two  inches  per  foot  up  to  45  degrees,  but  is  preferably  con- 
fined to  the  flatter  slopes;  steep  inclines  increase  the  expense  materially.  Slag  and 
gravel  roof  is  often  applied  to  reinforced  concrete  slabs  or  arches.  In  Continental 
Europe,  pumice  stone  is  occasionally  used  in  concrete  for  roof  purposes;  while  in 
America,  cinder  concrete  is  often  used  instead  of  gravel.  Both  of  these  concretes 
are  much  lighter  than  the  ordinary  gravel  concrete. 


POWER  PLANT  115 

In  constructing  a  gravel  roof,  the  concrete  is  first  covered  with  a  layer  of  hot  pitch 
over  which  is  laid  the  tarred  roofing  felt,  the  sheets  lapping  over  each  other  about 
half  the  width  of  the  roll,  and  each  sheet  being  mopped  with  pitch  as  it  is  laid.  Over 
the  entire  surface  an  even  layer  of  pitch  is  then  spread,  in  which,  while  still  hot, 
slag  or  gravel  is  embedded.  Another  well-designed  roof  requires  a  preliminary 
preparation  in  regard  to  the  steelwork  in  the  shape  of  T-irons  laid  over  the  roof 
purlins.  Between  these,  book  tiles  are  laid,  covered  with  Spanish  roll  tile.  The 
advantage  of  the  concrete  roof  construction,  and  the  two  latter  methods  mentioned, 
is  that  they  are  entirely  fireproof.  Steep  inclines  are  necessary  for  any  tile  or 
metallic  roof,  and  the  height  should  be  at  least  one-third  of  the  span.  Where  flat 
roofs  are  used,  surrounded  by  parapet  walls,  metal  flashing  should  be  provided. 


FIG.  ii. — Substation,  Stansstad,  Switzerland. 


For  tropical  countries,  the  pitch  and  gravel  roofs,  so  frequently  used  in  the  temperate 
zones,  are  not  suitable,  a  special  material  being  prepared  for  use  in  such  climates. 

One  of  the  troubles  with  corrugated  iron  roofing  arises  from  its  making  an  oven 
out  of  the  building  which  it  covers,  unless  an  air  space  is  provided  to  insulate  the 
room  directly  below  the  roof  from  the  heat,  which  may  be  done  by  applying  sheathing 
on  the  bottom  chords  of  the  roof  trusses.  This  sheathing  reduces  the  height  of 
the  room  and  increases  somewhat  the  difficulty  of  properly  ventilating  it.  Another 
trouble  with  corrugated  iron  roofs  arises  from  the  condensation  of  moisture  upon 
their  surface,  when  the  roof  for  any  reason  becomes  cooler  than  the  air.  This 
moisture  occasionally  causes  trouble  with  electrical  machinery. 


Il6  HYDROELECTRIC    DEVELOPMENTS   AND   ENGINEERING. 

Leaders.  One  square  inch  of  leader  area  must  be  provided  for  each  100  to  150 
square  feet  of  roof.  The  leaders  must  not  be  smaller  than  four  inches  in  diameter. 
In  ordinary  buildings,  galvanized  iron  leaders  are  used,  while  in  more  pretentious 
plants,  copper  of  rectangular  shape  is  sometimes  employed.  All  leaders  must  be 
provided  on  their  upper  ends  with  removable  guards  or  strainers. 

Doors.  The  door  through  which  material  is  received  should  .be  large  enough 
to  admit  a  railroad  car;  a  door  12  feet  wide  and  16  feet  high  will  suffice.  In  some 
cases,  Dutch  doors  are  used,  of  which  the  upper  half  can  be  used  for  ventilating 
purposes,  the  lower  half  remaining  closed.  When  it  is  desirable  to  open  the  whole 
door  at  once,  a  folding  gate  is  provided  to  keep  out  the  curious.  Swinging  doors 
are  for  many  reasons  inconvenient. 

There  are  on  the  market  various  designs  of  doors  for  economizing  room,  such  as 
vertical  and  horizontal  sliding  doors,  sectional  folding  and  rolling  doors.  The 
doors  should  be  ornamental  and  massive.  Oak,  well  paneled,  makes  a  very  hand- 
some door,  particularly  when  trimmed  with  bronze.  In  many  cases,  entire  metallic 
doors  of  ornamental  design  are  used,  as  it  is  desired  to  avoid  the  dull  appearance 
of  the  usual  fireproof  shutters. 

Windows.  The  generating  and  switching  room  must  have  abundant  light,  and 
large  windows  must  be  provided.  It  must  be  borne  in  mind,  however,  that  fireproof 
windows  cost  from  $0.80  to  $1.00  per  square  foot;  as  walls  are  always  calculated  by 
the  builder  as  solid,  the  cost  for  doors  and  windows  is  an  additional  expense.  It  is 
common  practice  to  have  the  windows  of  ribbed  wire  glass,  because  they  keep  out 
intense  rays  of  the  sun,  and  do  not  shatter  when  broken.  It  is  desirable  in  some 
localities,  to  protect  the  lower  windows  of  a  building  with  a  wire  mesh  or  bars.  The 
window  sashes  should  be  metallic  or  covered  with  metal. 

The  windows,  together  with  the  crane  pilasters,  must  be  symmetrical  with  regard 
to  the  arrangement  of  turbines.  Arched  windows  are  preferable  for  power  plants 
and  are  handsome  in  appearance.  If  the  windows  are  of  large  design,  care  must  be 
exercised  to  properly  panel  them  to  harmonize  with  the  design  of  the  building.  Too 
frequently,  the  design,  as  well  as  the  arrangement  of  windows,  spoils  the  appearance 
of  an  otherwise  well-designed  building. 

Stairways  and  Elevators.  Ample  stairway  provision  must  be  made,  because 
easy  access  to  all  points  is  essential.  The  stairways  should  be  about  4  feet  wide, 
have  easy  steps,  and  be  free  from  turns.  Where  the  floors  are  more  than  12  feet 
apart,  the  stairway  should  be  broken  by  a  landing.  Stairs  should  be  built  of  steel 
framing,  with  treads  of  checkered  steel,  slate,  or  covered  with  other  anti-slip  material. 
Where  elevators  are  installed,  to  eliminate  the  service  of  an  attendant,  they  must 
be  of  the  self-starting  control  type. 

Switchboard  Gallery.  The  switchboard  galleries  must  be  designed  to  give  plenty 
of  room  for  all  ducts  and  passages  necessary  for  wiring.  In  some  plants,  part  of  the 
flooring  is  made  up  of  slate  or  soapstone  slabs,  which  can  be  removed  should  the 
necessity  arise.  The  reason  for  employing  this  material  is,  that  such  stones  contain 
very  few  metallic  elements  and  are  first-class  insulators.  As  a  matter  of  precaution 


POWER  PLANT. 


117 


in  other  cases,  rubber  mats  are  sometimes  placed  on  the  floors  where  attendants 
have  to  stand,  while  operating  or  making  inspections. 

The  switchboard  itself  should  be  of  artistic  design,  harmonizing  with  the  costly 
instruments.  It  should  be  made  up  of  an  ornamental  iron  structure  faced  with  white 
marble  or  enameled  slate.  In  central  and  substations,  white  marble  panels  are 
more  in  vogue  abroad,  while  the  enameled  slate  is  favored  in  America.  All  instru- 
ments must  be  well  grouped.  When  instrument  pedestals  are  used,  they  must  be 
well  arranged,  and  at  the  same  time,  convenience  of  operation  must  not  be  sacrificed. 

Crane.  The  crane  is  not  an  architectural  feature,  but  even  this  unpromising 
subject  may  yield  to  proper  treatment.  It  should  be  designed  in  a  way  to  conform 
with  the  roof  trusses.  In  this  connection,  the  latticed  type  crane  has  a  better  appear- 
ance than  the  unsightly,  fish-bellied,  box  girder,  so  prominent  in  use. 

Heating.  If  the  plant  be  located  in  a  temperate  latitude,  it  will  be  necessary  to 
supply  means  for  heating.  The  most  common  means  are  by  steam  or  hot  water. 
The  latter  is,  however,  in  many  cases,  very  inconvenient,  due  to  the  large  amount 
of  radiating  surface  necessary;  there  is  also  the  danger  of  freezing  exposed  pipes. 
Steam  heating  is  far  better  for  a  large  building,  being  more  economically  installed 
and  more  easily  handled.  There  are  two  systems  of  steam  heating  which, may,  l?e 
used  that  will  produce  satisfactory  results,  viz.,  direct  radiating  system  and  hot 
blast.  With  the  direct  radiating  system,  the  heating  may  be  done  either  by  pipe 
coils  or  radiators  or  a  combination  of  both.  The  coils  may  be  located  either  on 
the  ceiling  or  under  the  windows;  the  latter  method  is  the  more  efficient,  the  neces- 
sary radiating  surface  being  about  10  per  cent  less  than  that  of  ceiling  coils.  A 
table  for  calculating  the  necessary  amount  of  radiating  surface  to  heat  a  room  of 
given  dimensions  is  given  in  Table  I. 

TABLE    I.  —  FACTORS    FOR    RADIATING    SURFACES. 


iladiatoi 

S. 

Coils. 

Outside  temperature. 

0 

0 

o 

o 

0 

0 

0 

o 

O 

0 

Inside  temperature. 

45 

54 

63 

72 

Si 

45 

54 

63 

7* 

81 

4-inch  brick  wall  

.112 

•  137 

•  I7I 

.209 

.156 

.095 

.121 

•  I5I 

.182 

.226 

8-inch  brick  wall  

.076 

•  OQ3 

.  106 

•  143 

•  174 

.064 

.082 

.  102 

•  I25 

•  145 

12-incb  brick  wall  

.O?2 

.06? 

.081 

.099 

.  121 

.045 

.057 

.072 

.088 

.  107 

1  6-inch  brick  wall  

•  O43 

•  O^ 

.066 

.081 

.098 

.036 

.046 

.058 

.072 

.087 

2o-inch  brick  wall  

.078 

.046 

.058 

.072 

.087 

.032 

.041 

.052 

.063 

.077 

24-inch  brick  wall  

•O33 

.041 

.OC.I 

.063 

.076 

.028 

.036 

•°45 

.055 

.067 

28-inch  brick  wall  

.O2Q 

.036 

.04? 

.054 

.064 

.025 

.031 

.028 

.048 

.056 

Window,  single  

•  I99 

.241; 

.  306 

•  377 

.458 

.  169 

.214 

.270 

.331 

•403 

Window,  double  

-  004 

.  IOC. 

•  *44 

.178 

.215 

•°79 

.  102 

.  127 

.156 

.  190 

Skylight,  single  

.18? 

.  22? 

.282 

.348 

.421 

.156 

.199 

.249 

.305 

.371 

Skylight,  double  

.  IO2 

.12? 

•  J57 

•  J93 

.234 

.087 

.III 

.138 

.  169 

.  206 

Floor,  wood  

.OI4 

.Ol8 

.021 

.027 

.032 

.012 

.015 

.018 

.023 

.028 

Ceiling,  wood  

.Ol8 

.O2I 

.027 

.033 

.041 

.015 

.OI9 

.  O24 

.  029 

.035 

Floor,  fireproof  

.O2O 

.026 

.032 

.039 

.047 

.018 

.022 

.029 

.035 

.042 

Ceiling,  fireproof  

.024 

.029 

.037 

.045 

.055 

.O2O 

.027 

.033 

.041 

.048 

Door  

.068 

.084 

.  10? 

.  129 

.156 

.058 

.074 

.  092 

•  II3 

.138 

Cubics  

.OO4 

.OO? 

.006 

.007 

.008 

.003 

.004 

.OO5 

.006 

.007 

Ii8  HYDROELECTRIC    DEVELOPMENTS   AND   ENGINEERING. 

The  method  of  using  this  table  is  as  follows:  Calculate  the  amount  of  exposed 
wall  and  glass  surface  in  square  feet,  and  figure  the  cubic  contents  of  the  room. 
Multiply  these  results  by  the  various  amounts  shown  under  the  headings  for  the 
temperature  desired;  the  sum  of  the  results  will  be  the  number  of  square  feet 
of  heating  surface  necessary.  It  will  be  noticed  that  the  table  calls  for  an 
outside  temperature  of  o°F.;  it  is  general  practice  to  figure  this  temperature  as  the 
minimum. 

Hot  blast  heating  is  done  by  blowing  air,  by  means  of  fans,  over  coil  surface 
and  transmitting  the  heated  air  to  various  points  of  discharge  by  means  of 
galvanized  iron  ducts.  There  are  two  methods  of  doing  this,  —  one  by  recirculat- 
ing  the  air,  that  is,  using  the  air  in  the  room  over  and  over  again.  The  other 
method  costs  more  to  operate,  but  insures  better  ventilation,  as  it  supplies  heated 
outside  air. 

The  style  of  boiler  to  be  used  depends  entirely  upon  the  size  of  the  plant;  up  to 
25  HP.  a  cast-iron  sectional  boiler  will  produce  good  results;  up  to  100  HP.  a 
;hprizpntal  tubular  or  a  locomotive  boiler  is  as  good  as  can  be  used;  anything  over 
this; '  a  .water  tube  boiler  will  be  found  most  economical.  It  is  advisable  to  locate 
the  btojler  in  a  separate  building,  in  order  to  remove  any  possibility  of  dust  and  ashes 
accumulating  on  the  machines. 

For  calculating  the  size  of  the  boiler,  100  square  feet  of  radiating  surface  to  one 
boiler  horsepower  (30  pounds  of  steam  per  hour)  for  direct  radiation  is  the  accepted 
practice.  For  blast  coil  work,  a  rough  rule  is  30  square  feet  of  radiating  surface 
per  boiler  horsepower.  This  latter,  however,  is  inaccurate,  as  there  are  numerous 
other  conditions,  such  as  shape  of  heaters,  number  of  air  changes  per  hour,  etc., 
which  must  be  taken  into  consideration.  The  steam  mains  supplying  the  heating 
system  may  be  calculated  on  the  following  velocities:  5000  to  6000  feet  for  the  main 
distributing  lines;  3000  to  3500  feet  for  vertical  rising  lines,  and  1200  to  1500  feet 
for  individual  branch  mains.  No  branch  main  should  be  less  than  i-inch  pipe. 
These  velocities  are  for  low-pressure  steam.  The  return  mains  are  generally  one- 
third  to  one-half  the  size  of  the  supply  mains.  Careful  provision  must  be  made  that 
all  piping  pitches  in  the  direction  of  the  flow  of  steam;  this  pitch  must  be  at  least 
three-fourths  inch  in  every  10  feet. 

It  is  important  to  cover  all  supply  and  return  mains  with  a  good  non-conductor, 
not  only  for  economy's  sake,  but  also  to  minimize  the  fall  in  pressure  in  the  steam 
main  which  often  produces  snapping  and  cracking  in  the  pipe. 

Ventilation.  For  ventilating  generating  room,  louvres  with  swinging  windows 
should  be  avoided  in  the  roof,  above  or  near  current-carrying  apparatus  such  as 
generators,  motors  or  switchboards.  The  windows  in  the  wall  on  the  switchboard 
side  must  be  fastened,  no  provision  being  made  to  open  same,  or  else  a  locking 
system  provided.  This  precaution  must  be  taken  to  prevent  short-circuits  caused 
by  rain  and  dust  particles,  blown  in  from  the  outside. 

Where  air  blast  transformers  and  storage  batteries  are  installed,  forced  draft 
must  be  used;  the  discharge  gases  of  the  latter  must  be  carried  through  special  ducts 
up  through  the  roof. 


119 


POWER  PLANT. 

Lighting.  To  provide  for  an  emergency,  in  case  of  a  complete  shut  ( 
generating  and  switching  room  must  be  provided  with  a  multiple  systemltrf  wiring:' 
This  is  essential,  for  instance,  in  the  alternating  current  plant  with  motor-driven 
exciters;  a  complete  shut-down  would  seriously  handicap  the  locating  of  the  trouble. 
In  modern  plants,  the  switch  gear  is  operated  by  motors,  supplied  by  a  storage 
battery  which  may  furnish  light  also.  As  much  as  possible,  wires  must  be  concealed 
and  run  in  ducts  of  approved  design. 

Lavatories.  For  sanitary  reasons,  well-equipped  lavatories  must  be  installed 
in  all  plants.  The  plumbing  must  be  of  good  substantial  material,  enameled  basins, 
bowls  or  sinks.  Bowls  are  preferable  to  sinks;  bath  and  toilet  floors  should  be  tiled; 
the  partitions  of  white  enameled  slate,  or,  if  a  more  expensive  construction  is  desired, 
of  marble.  The  advantage  of  white  finish  is,  that  it  enforces  cleanliness  by  making 
dirt  conspicuous.  The  drain  must  run  to  avoid  all  ducts  and  wiring,  and  be 
properly  provided  with  traps  and  vent  pipes;  the  latter  must  extend  above 
the  roof. 

Preferably  at  the  side  of  lavatories,  lockers  should  be  installed  to  enable  the  men 
to  change  their  clothes  and  clean  up.  The  lockers  must  be  large  enough  to  contain 
a  complete  change  of  clothing,  permitting  a  man  in  winter  to  hang  up  an  overcoat. 
Sufficient  room  must  be  given  in  the  aisles  to  allow  the  men  to  make  necessary 
changes. 

Conclusions.  Many  have  biased  opinions,  that  by  the  erection  of  power  plants 
for  the  utilization  of  water  power,  the  scenery  of  the  country  will  be  destroyed. 
It  is  an  entirely  mistaken  idea.  It  is  only  a  matter  of  ability,  on  the  part  of  the  engi- 
neer and  architect,  to  design  a  plant  to  harmonize  with  the  surroundings.  In  fact, 
plants  have  been  installed,  greatly  enhancing  the  beauty  of  the  scenery  of  the  country. 
To  bear  out  this  statement,  illustrations  are  given  in  Figs.  12  and  13.  The  latter  is 
the  head  race  of  the  i5,ooo-HP.  plant  utilizing  the  water  of  the  Sill,  near  Innsbruck, 
Tyrol.  The  valley  without  the  canal,  spillway,  and  building  for  attendants,  would 
undoubtedly  be  monotonous,  particularly  in  the  mountainous  country.  Considering 
Fig.  14,  the  power  plant  at  Tivoli  on  the  Tiber,  it  is  perhaps  the  most  picturesque 
power  plant  ever  designed.  The  building  itself  with  its  few  arched  openings  is 
simple;  the  head-race  is  designed  after  the  style  of  the  old  Roman  aqueducts,  and 
carries  more  water  than  the  power  plant  needs.  Without  question,  the  scenic  value 
of  the  country  has  been  increased.  This  is  more  remarkable,  because  the  plant  was 
not  erected  for  the  immediate  locality,  but  to  serve  the  city  of  Rome. 

It  cannot  be  expected  that  all  plants  should  be  architecturally  treated  in  the 
same  manner  as  some  of  the  above  cited.  However,  it  must  always  be  remembered 
that  a  pleasing  appearance  can  be  secured  at  little  or  no  additional  expense.  In 
fact,  many  prominent  plants  which  are  masterpieces  of  ugliness,  have  cost  more 
per  unit  capacity  than  those  which  are  noted  for  their  fine  appearance;  a  proper 
knowledge  of  architecture  being  requisite  to  secure  good  results. 


A.E.&M.E 


FIG.  12— Bird's-Eye  View  of  "Sillwerke,"  Tyrol. 


(120) 


FIG.  13.— Headrace  of  the  "Sillwerke,"  Tyrol. 


POWER  PLANT. 


121 


By  courtesy  of  the  Proprietor  of  Gassier' s  Magazine. 


FIG.  14.— Tivoli  Plant,  Rome,  Italy. 


122 


HYDROELECTRIC    DEVELOPMENTS    AND   ENGINEERING. 


STRUCTURAL    STEEL. 

Roof  Trusses.  As  it  is  essential  that  structures  be  fireproof,  first  of  all,  structural 
steel  roof  trusses  are  required.  In  small  plants,  the  roof  trusses  are  preferably 
carried  on  the  side  walls;  while  in  large  plants,  the  trusses  are  carried  on  columns, 
which  support  also  the  crane  runway.  The  outline  of  the  roof  trusses  depends 
upon  the  kind  of  roof  to  be  supported  and  the  pitch,  which  depends  also  upon 
architectural  conditions.  When  slate  and  shingles  are  the  only  roofing  materials 
available,  steep  slopes  are  necessary,  in  order  to  cause  the  water  to  run  off  rapidly, 
and  prevent  its  working  up  under  the  roof  and  causing  leaks.  With  modern  methods 
of  waterproofing,  a  slope  of  2  inches  per  foot  is  sufficient  to  supply  the  requisite 
drainage.  Such  roofs  have  many  advantages:  they  require  less  material  than  those 
of  steeper  pitch;  also,  they  are  easier  to  build,  and  the  waterproofing  is  readily  applied. 
Steeper  roofs,  however,  are  often  used,  owing  to  the  fact  that  they  are  considered 
more  economical  in  steel,  but  this  advantage  is  more  than  offset  by  applying  the 
roofing. 


•-e. 


^uo.1      Panels.  - 


FIGS,  i  to  4. — Typical  Roof  Trusses. 

The  accompanying  sketches,  Figs,  i  to  4,  illustrate  some  of  the  usual  forms 
employed  in  roof  construction.  An  inspection  of  the  various  cross  sections  of  plants 
given  in  different  parts  of  this  volume,  show  a  number  of  other  forms  of  roof  trusses 
in  actual  use,  some  of  which  are  more  or  less  ornamental.  In  the  design  of  roof 
trusses,  it  is  necessary  to  know  the  span  and  the  load  as  well  as  the  spacing  of  the 
trusses.  In  power  plant  work,  the  location  of  columns  is  largely  determined  by 
the  equipment.  For  the  sake  of  rigidity,  the  trusses  must  be  directly  connected  to 
the  columns;  it  will  therefore  be  seen  that  the  span  and  distance  between  trusses  is 


POWER  PLANT.  123 

fixed,  and  that  this  distance  may  or  may  not  permit  the  most  economical  design 
of  truss.  The  loading  depends  upon  the  locality  of  the  plant,  and  the  style  of  roof 
to  be  used.  In  New  York  City,  the  live  load  of  a  roof  having  a  pitch  less  than  20  per 
cent,  is  50  pounds  per  square  foot,  and  for  a  pitch  exceeding  20  per  cent,  is  30  pounds 
per  square  foot.  This  live  load  (snow  and  wind)  is  the  vertical  component  on  the 
projected  area.  In  localities  subject  to  severe  wind  storms,  the  roofs  must  be 
properly  anchored,  particularly  when  they  rest  on  walls.  The  top  chords  of  the 
trusses  are  tied  together  by  purlins,  which  support  the  roof;  on  deep  trusses,  the 
lower  chords  have  longitudinal  bracing.  In  addition,  at  the  end  panels,  and  in  long 
buildings  at  intermediate  panels,  angles  or  chords  are  used  for  diagonal  bracing  in 
the  plane  of  the  upper  and  lower  chords.  An  overhead  crane,  operated  by  power 
or  hand,  is  essential  in  the  generating  room,  also  in  the  transformer  room  of  larger 
power  houses.  In  brick  buildings,  the  crane  runways  may  be  supported  on  pilasters 
of  the  wall  designed  for  this  purpose.  This  type  of  construction  is  adopted  only 
in  small  and  comparatively  low  buildings,  or  in  localities  where  masonry  is  cheaper 
than  structural  steel. 

In  localities  where  building  materials  are  expensive,  it  is  better  to  erect  a  corru- 
gated sheet  steel  iron  frame  structure.  This  is  particularly  true  in  tropical  countries 
where  the  labor  and  building  materials  have  to  be  imported.  For  this  type  of 
building,  galvanized  corrugated  iron  is  used,  Nos.  18  and  24  gauge,  and  for  the  roof, 
Nos.  20  to  26  (United  States  Standard).  The  siding  is  in  all  cases  two  gauges 
lighter  than  that  of  the  roofing.  Black  or  painted  sheets  are  occasionally  used,  but 
as  they  are  not  so  durable  as  the  galvanized  sheets,  they  cannot  be  recommended. 
The  best  grade  of  this  material  is  called  "Muck  Bar"  corrugated  sheeting,  and  is 
much  more  durable  when  exposed  to  moist  air.  A  corrugated  iron  building  can 
hardly  be  classified  as  a  permanent  structure,  and  cannot  be  recommended  for  modern 
power  plant  practice.  There  are  several  methods  in  use  for  the  design  of  structural 
steel  buildings.  In  one,  the  frame  is  self-supporting,  and  the  light  curtain  walls  are 
partly  supported  by  the  steelwork;  while  on  the  other  hand,  the  structural  steel,  as 
well  as  the  walls,  is  entirely  self-supporting. 

Columns.  The  building  columns  should  be  of  the  open  type  as  much  as  possible 
(see  Figs.  5  to  7).  The  use  of  box  girders  and  columns  should  be  avoided,  because 


~r         T        r 

i 


FIGS.  5  to  7. — Typical  Columns. 

they  are  usually  built  up  of  channels,  I-beams  and  plates,  and  are  more  apt  to  corrode 
inside  than  out,  as  they  cannot  be  painted  inside;  to  overcome  corrosion,  they  may 
be  filled  with  concrete. 

Column  Bases.   The  columns  are  preferably  designed  with  a  base  of  sufficient 
area  to  permit  of  their  being  set  directly  upon  the  foundation,  but  cast-iron  base 


124  HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 

plates  are  sometimes  interposed  at  this  point,  as  they  can  be  leveled  up  before  the 
column  is  erected.  Grillages  are  undesirable,  but  cannot  be  avoided  with  heavy 
column  loads. 

Floors.  In  hydraulic  plants,  little  use  is  made  of  floorbeams  as  far  as  the 
generating  room  is  concerned;  the  whole  substructure  is  made  of  solid  concrete. 
However,  in  the  design  of  the  floors  in  the  switching  and  transformer  rooms,  con- 
siderable structural  steel  is  used.  In  many  cases,  the  floors  are  subjected  to  concen- 
trated local  loads  at  various  points,  which  require  special  treatment.  In  other  cases 
a  railroad  spur  extends  into  the  building,  to  facilitate  the  handling  of  heavy  material 
by  an  overhead  crane.  The  load  for  which  the  floors  must  be  designed,  is  the  weight 
of  the  heaviest  pieces  of  machinery  placed  on  them.  It  must  be  borne  in  mind,  that 


'•  ' 


,    ',  '  - 

•///'  -'\/  ''/*•*  i.'*.'.*'  /  / 

'///s'LSsL-  ////////. 


FIG.  8. — Crane  Column. 

during  construction,  large  quantities  of  material  are  apt  to  be  piled  on  the  floor, 
consequently  precautions  must  be  taken.  As  the  weights  of  the  various  pieces  of 
machinery,  such  as  generators,  transformers,  etc.,  change  so  very  greatly  with  their 
functions,  this  data  must  be  obtained  from  the  manufacturer. 

In  countries  where  only  the  lowest  grade  of  labor  can  be  obtained,  and  conditions 
do  not  warrant  the  sending  of  an  erecting  force,  but  only  a  foreman,  the  steel  sections 
may  be  bolted  together  and  filled  instead  of  being  riveted.  Experience  has  shown 
in  some  cases,  that  abutting  pieces  had  to  be  provided  with  dowel  pins  to  facilitate 
erection. 

The  use  of  floor  arches  causes  a  lateral  thrust  against  all  of  the  beams  composing 
the  floor  system;  for  this  reason  it  is  necessary  to  introduce  tie  rods,  suitably  spaced, 
to  take  care  of  this  stress.  These  tie  rods  should  always  be  placed  high  enough  so 
that  they  will  be  hidden  by  the  floor  arches,  as  this  adds  greatly  to  the  appearance  of 
the  ceilings.  In  some  plants  this  detail  has  been  neglected,  and  the  result,  to  say  the 
least,  is  unsightly.  Another  small  point,  is  the  provision  of  curb  angles  around  all 
hatches  and  other  openings  in  the  floors;  these  angles  should  project  from  2  to  3 
inches  above  the  finished  floor  level,  their  purpose  being,  to  prevent  wash  water, 
sweepings,  etc.,  going  down  to  the  floor  below.  The  value  of  these  curbs  is  more 
apparent  in  those  cases  where  machinery  is  located  on  the  lower  floors,  or  under  the 
galleries,  which  would  be  liable  to  damage  from  anything  dropping  on  to  them. 

Expansion  Joints.  In  very  long  buildings,  the  expansion  due  to  changes  of  tem- 
perature must  be  taken  care  of  during  erection,  but  such  precautions  are  not  required 


POWER  PLANT.  125 

in  small  buildings.  In  buildings  under  300  feet  in  length,  temperature  variations 
do  not  cause  much  trouble,  and  no  special  precautions  are  required  to  care  for  them. 
In  some  cases,  where  expansion  joints  are  used,  it  is  specified,  that  after  the  building 
has  been  walled  in,  the  joints  shall  be  blocked  with  lead  to  prevent  any  motion  of 
the  steelwork  cracking  the  concrete  flooring,  etc.  The  necessity  of  these  joints  is 
only  during  the  erection  period,  when  longitudinal  expansion  is  very  apt  to  make 
it  difficult  to  erect  portions  of  the  steelwork. 

Fiber  Stresses.  Steel  structures  are  proportioned,  in  regard  to  the  sections  used, 
by  a  limit  set  on  the  fiber  stress  in  tension,  which  is  reduced,  for  compression 
members,  usually  by  Gordon's  formula.  In  many  localities,  the  limiting  unit 
stresses  are  specified  in  the  building  laws,  these  in  some  cases  being  limited  in  their 
application,  to  some  particular  city;  in  other  cases,  they  apply  to  a  state  or  nation; 
the  legal  requirements  differ  greatly  in  different  localities,  hence  it  is  advisable  to 
investigate  the  subject  unless  the  requirements  are  well  known.  In  practice,  the 
fiber  or  unit  stresses  for  steel  in  tension  vary  from  13,500  to  20,000  pounds  per  square 
inch;  for  most  of  the  important  structures,  the  working  stresses  have  been  kept 
between  15,000  and  16,000  pounds  per  square  inch. 

Character  of  Steel.  A  large  portion  of  the  structural  steel  manufactured  in  the 
United  States  is  made  under  the  "Manufacturers'  Standard  Specifications"  as 
revised  to  Feb.  6,  1903,  which  permit  the  use  of  either  open-hearth  (Siemens- 
Martin)  or  Bessemer  steel  (the  Bessemer  steel  produced  in  the  United  States  is  made 
by  the  acid  process,  no  basic  Bessemer  steel  being  produced).  The  practice  of 
specifying  open-hearth  steel  exclusively,  for  most  structures,  is  growing,  owing  to  the 
fact  that  it  is  more  homogeneous  in  its  physical  properties.  Bessemer  steel,  on  the 
contrary,  is  liable  to  fail  in  service,  in  an  irregular  and  inexplicable  manner,  and  for 
this  reason  it  is  not  desirable  for  structural  work. 

All  steel  made  by  the  open-hearth  process  must  be  of  uniform  quality,  tough  and 
ductile.  The  phosphorus  must  not  exceed  0.08  per  cent.  Rivet  steel  must  have 
an  ultimate  tensile  strength  of  from  45,000  to  55,000  pounds  per  square  inch. 
Structural  steel  must  have  an  ultimate  tensile  strength  of  from  55,000  to  65,000 
pounds  per  square  inch.  The  elastic  limit  must  not  be  less  than  one-half  of  the 
ultimate  tensile  strength. 

The  percentage  of  elongation  must  be  equal  to: 

1,400,000 


Ultimate  strength  in  pounds  per  square  inch 

Rivet  steel,  before  or  after  heating  to  a  light  yellow  heat  and  quenching  in  cold 
water,  must  stand  bending  180  degrees  flat  on  itself,  without  signs  of  fracture. 
Structural  steel,  before  or  after  heating  to  a  light  cherry-red  heat  and  quenching 
in  cold  water,  must  stand  bending  180  degrees,  to  a  curve  whose  diameter  does  not 
exceed  the  thickness  of  the  sample,  without  signs  of  fracture.  The  finished  bar  plate 
and  shapes  must  be  free  from  all  cracks,  flaws,  seams,  blisters  and  all  other  defects; 
it  must  have  a  smooth  surface  and  be  well  straightened  at  the  mill  before  shipment. 
The  tensile  strength,  limit  of  elasticity  and  ductility  must  be  determined  from 


126  HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 

standard  test  pieces,  of  at  least  one-half  square  inch  sectional  area,  cut  from  the 
finished  material;  two  opposite  sides  of  the  test  piece  must  be  the  rolled  surface, 
the  other  two  opposite  surfaces  to  be  milled  or  planed  parallel;  rivet  rounds,  however, 
must  be  tested  of  the  full  size,  as  rolled.  All  test  pieces  must  show  a  fracture  of  a 
uniform  fine-grained,  silky  appearance,  of  a  bluish  gray  or  "dove''  color,  and  must 
be  entirely  free  from  granular,  brilliant  and  black  specks  of  a  fiery  luster.  Every 
finished  piece  must  be  clearly  stamped  with  the  melt  numbers. 

The  inspection  of  the  steel,  to  insure  its  compliance  with  the  specifications, 
necessarily  takes  place  at  the  mill.  It  is  common  to  introduce  a  clause  in  the 
specifications,  by  which  if  any  material  accepted  at  the  mill,  when  under  the  punches 
or  shears,  shows  that  it  is  not  of  uniform  quality,  it  may  be  rejected  at  the  shops.  In 
some  cases  a  drifting  test  is  called  for,  by  which  a  hole  punched  in  a  plate  or  piece, 
the  thickness  of  the  material  in  some  cases  being  specified,  can  be  drifted  to  a 
larger  diameter,  without  cracking  either  the  edges  of  the  hole  or  the  external  edge 
of  the  piece,  the  increase  in  the  diameter  of  the  hole  ranging  from  one-third  to 
one-half  the  original.  The  distance  from  the  center  of  the  hole  to  the  edge  of  the 
piece  may  be  specified. 

Workmanship.  The  following,  in  reference  to  workmanship,  is  based  on  the 
standard  practice  of  some  of  the  leading  concerns.  All  material  must  be  punched 
one-sixteenth  of  an  inch  larger  than  the  nominal  size  of  the  rivets,  except  that 
material  five-eighths  of  an  inch  thick  and  over,  must  be  drilled  or  subpunched  and 
reamed  one-eighth  of  an  inch  larger  in  diameter,  so  as  to  remove  all  sheared  or 
burred  edges.  (In  some  cases  subpunching  is  insisted  upon  when  more  than  one 
cover  plate  is  used  on  columns  or  girders,  in  which  case  the  reaming  must  be  done 
after  the  parts  are  assembled  and  clamped  together.) 

All  work  must  match  so  accurately,  that  after  assembling,  the  rivets  can  be 
entered  without  drifting. 

Whenever  possible,  all  rivets  should  be  machine  driven  by  direct  acting  machines, 
operated  by  compressed  air,  steam  or  hydraulic  pressure,  which  should  be  capable 
of  retaining  the  applied  pressure  after  the  upsetting  has  been  completed.  Field 
riveting  should  be  done,  preferably,  by  long-stroke  pneumatic  riveters.  Hand 
riveting  should  not  be  permitted  for  rivets  over  seven-eighths  of  an  inch  in  diameter. 

The  details  must  be  designed  to  avoid  riveting  in  difficult  or  inaccessible  places. 
No  bolts  should  be  used,  except  by  permission;  they  must  be  turned  to  a  driving 
fit,  and  the  bolt  holes  drilled  and  reamed  after  the  parts  are  assembled  and  clamped 
together.  In  many  cases,  however,  the  roof  purlins  are  bolted  with  ordinary  black 
bolts,  all  other  connections  being  riveted.  The  abutting  surfaces  of  compression 
members  must  be  truly  faced  to  an  even  bearing.  (In  some  cases  this  clause  is 
extended  to  cover  the  tops  of  column  bed  plates  in  a  specific  manner,  and  in  some 
rare  instances  it  is  specified  that  the  abutting  ends  of  tension  members  must  be 
faced.) 

All  rivets,  when  heated  and  ready  for  driving,  must  be  clean.  When  driven,  they 
must  completely  fill  the  hole  and  have  round  concentric  heads  of  uniform  size, 
thoroughly  pinching  the  connected  pieces. 


POWER  PLANT.  127 

Inspection.  All  facilities  for  the  inspection,  testing  of  material  and  workmanship, 
must  be  furnished  by  the  contractor  to  duly  appointed  inspectors,  but  the  inspection 
for  the  raw  materials  must  be  made  at  the  mills  or  foundries  where  the  steel  is 
rolled  or  the  castings  made.  The  inspectors  must  be  allowed  free  access  to  all 
portions  of  the  plant  in  which  any  portion  of  the  material  is  made. 

Painting.  In  regard  to  painting,  there  are  a  number  of  differing  requirements, 
such  as,  raw  and  boiled  linseed  oil,  iron  ore  or  iron  oxide  paint,  red  lead  paint, 
graphite  paint,  etc.,  and  there  are  a  number  of  proprietary  mixtures  on  the  market 
of  more  or  less  value.  The  proportion  of  the  materials  to  be  used  in  preparing  the 
paint,  and  the  kind  of  brushes  to  be  used  in  applying  it,  are  sometimes  enumerated. 
The  proportion  of  red  lead  used,  varies  from  16  to  40  pounds  per  gallon  of  oil, 
depending  upon  the  quality;  a  paint  containing  25  pounds  of  red  lead  per  gallon 
of  oil  makes  a  very  satisfactory  coating  for  steel,  the  following  formula  being  a 
very  good  mixture: 

25  pounds  of  pure  red  lead, 
i  gallon  of  pure  raw  linseed  oil, 
|  pint  of  japan,  free  from  benzine. 

Iron  ore  or  oxide  paints  possess  the  merit  of  being  cheap,  and  for  this  reason 
are  much  used.  They  are  not  reliable,  and  should  be  avoided  in  good  practice. 
Boiled  linseed  oil  without  a  pigment  makes  a  good  coating  for  iron  or  steel.  The 
pigment  addition  acts  as  a  filler  for  the  pores  in  the  oil,  and  retards  its  drying  or 
oxidization,  and  for  this  reason  driers  are  used,  japan  being  one  of  the  best  materials 
for  this  purpose,  provided  it  is  free  from  benzine.  The  use  of  benzine,  sometimes 
called  gasolene  or  naphtha,  must  not  be  permitted  in  any  paint  which  is  to  be  applied 
to  ironwork,  for  the  rapid  evaporation  of  the  benzine  will  cool  the  material  to  a 
point  where  the  surface  to  be  painted  will  be  covered  with  a  dew  or  moisture.  At 
least  48  hours  must  elapse  between  the  application  of  each  coat  of  paint.  Painting 
should  not  be  permitted  during  freezing  or  wet  weather.  The  writer  would  be 
inclined  to  specify  that  painting  should  only  be  permitted  on  clear  days,  when  the 
temperature  was  above  40°  F.  In  riveted  work,  all  surfaces  coming  in  contact 
must  be  painted,  before  assembling,  with  one  coat  of  paint  on  each  surface. 
Occasionally  it  is  specified  that  all  portions  of  the  work  to  be  embedded  in  concrete 
or  brickwork  must  receive  one  or  two  coats  of  asphaltum  varnish.  All  the  work 
must  receive  at  least  one  coat  of  paint  before  it  is  shipped;  and  after  erection,  all 
places  where  the  paint  has  been  rubbed  off,  and  the  heads  of  the  field  rivets,  must  be 
painted,  after  which  the  entire  structure  must  receive  two  coats  of  paint. 

There  is  very  little  agreement  in  regard  to  the  best  coating  for  any  particular 
case,  probably  because  so  much  depends  upon  the  preparation  of  the  surface  to 
receive  the  paint,  the  care  with  which  it  is  applied,  and  the  exposure  conditions. 

All  dust  and  loose  scale  must  be  removed  before  the  paint  is  applied,  and  the 
painter  should  follow  immediately  after  the  cleaner. 

Prevention  of  Electrolysis.  At  various  times  it  has  been  proposed  to  insulate  the 
steel  frames  of  power  houses,  with  the  idea  of  preventing  electrolytic  action.  The 


128  HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 

complete  insulation  of  the  frame  is  impractical,  owing  to  the  fact  that  a  number  of 
pipes  must  be  supported  by  hangers  bolted,  or  otherwise  secured,  to  the  framing; 
some  of  these  pipes  being  in  connection,  electrically,  with  the  ground  water,  an 
attempt  at  insulation  is  extremely  liable  to  localize  the  electrolytic  action  at  a  few 
points,  which  would  be  worse  than  the  troubles  arising  from  the  entire  omission  of 
insulation. 

At  the  site  of  erection,  or  adjacent  thereto,  it  is  usually  necessary  to  store  portions 
of  the  structural  material,  after  it  is  unloaded  and  until  it  is  required  for  erection. 
This  material  must  be  laid  on  skids,  so  that  it  does  not  come  in  contact  with  the 
ground  and  must  be  kept  clean. 


CHAPTER   VI. 
MECHANICAL   EQUIPMENT. 

TURBINES. 

Classification.  As  regards  the  behavior  of  the  water,  turbines  may  be  divided 
into  two  general  types,  the  reaction  and  impulse.  In  the  former,  the  flow  of  water 
must  be  continuous  in  all  parts  of  the  turbine,  that  is,  the  entire  runner  is  under 
water;  in  the  impulse  type,  the  water  impinges  on  parts  of  the  wheel,  and  in  nearly 
all  cases  the  atmospheric  air  has  free  access  to  the  remainder  of  the  runner.  Turbines 
may  be  further  divided  as  regards  their  construction,  into  radial,  axial  or  parallel 
flow  and  combined  or  mixed  flow.  In  the  radial  type,  the  water  passes  through 
the  wheel,  either  inward  or  outward  at  right  angles  to  the  axis  of  rotation.  In  the 
axial  turbine,  the  general  direction  is  parallel  to  the  axis  of  rotation.  In  the  mixed 
flow  turbine,  the  water  enters  radially  and  discharges  axially,  or  vice  versa.  The 
different  types  of  reaction  turbines  are  commonly  known  by  the  names  of  their 
inventors,  as  the  Fourneyron,  which  is  a  radial  outward  flow;  the  Francis,  a  radial 
inward  flow;  and  the  Jonval,  a  parallel  flow.  A  combination  of  the  Jonval  and 
Francis  is  known  as  the  American  type,  and  is  to-day  the  most  common  one  used 
in  America,  where  it  had  its  origin.  Of  the  impulse  type,  the  Girad  and  the 
Zuppinger  in  Europe  and  the  Pelton  in  America  are  the  most  familiar.  In  regard 
to  the  origin  of  the  impulse  wheel,  it  might  be  of  interest  to  state,  that  Zuppinger 
in  1846  installed  his  first  tangential  wheel  at  Weiler's  Mills  near  Friedrichshafen  on 
Lake  Constance.1  The  same  engineer,  who  was  at  the  time  connected  with  the 
Escher  Wyss  Company,  built  in  1868-69  for  the  Haemmerle  Cotton  Mill  in  Dornbirn, 
Voral  Mountains,  Germany,  a  tangential  turbine  of  220  H.P.,  making  300  R.P.M. 
under  a  head  of  550  feet.2  This  tangential  impulse  wheel  was  5  feet  in  diameter, 
30  inches  wide,  and  mounted  upon  a  vertical  shaft  and  provided  with  two  diametri- 
cally opposite  jets  or  nozzles;  it  was  designed  for  a  water  supply  varying  from  one 
to  six  cubic  feet  per  second,  and  as  the  designer  up  to  that  time  had  not  constructed 
wheels  to  operate  with  over  380  feet  head,  he  thought  it  advisable  not  to  give  a 
guarantee  of  more  than  65  per  cent.  However,  during  actual  operation,  with  a 
water  consumption  of  1.5  to  2  cubic  feet  per  second,  the  efficiency  was  70  to  75  per 
cent;  with  a  water  consumption  of  about  5  cubic  feet  per  second,  was  65  to  70  per  cent. 

Turbines  are  also  classified  as  follows: 
I.  Low  head  —  up  to  30  feet. 
II.  Medium  head  —  from  30  to  200  feet. 

III.  High  head  —  above  200  feet. 

1  Letter  by  Prof.  Escher,  Zeitschrift  des  Vereines  deutscher  Ingenieure,  Feb.  18,  1905. 
3  Grosse  moderns  Turbinenanlagen.     L.  Zodel,  Schweitzerische-Bauzeitung,  June  13,  1908. 

.      129 


130 


HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 


This  classification  is  not  strictly  adhered  to,  as  many  manufacturers  and  plant 
designers  are  ignorant  of  the  fact  that  a  low  head  turbine  is  less  efficient  when 
applied  to  a  high  head,  and  vice  versa.  Reputable  manufacturers  with  competent 
engineering  staffs  will  advise  the  use  of  such  a  turbine  as  is  most  suitable  for  the 
condition  at  hand.  Slight  variations  of  the  above  are  sometimes  made,  when  other 
conditions  favor  the  same.  A  rigid  classification  by  European  engineers  is  as 
follows:  1 

Low  head  turbine,  up  to  about  10  feet. 

(With  open  flumes,  vertical  shafts  with  bevel  gearing.  When  above  ground  water, 
horizontal  shaft  with  belt  or  rope  drive.) 

First  intermediate  head  turbine,  from  10  feet  to  about  35  feet.  (Open  penstock, 
which  is  possible  up  to  35  feet;  vertical,  or  when  advisable,  horizontal  shaft.) 

Second  intermediate  head  turbine,  from  35  to  about  165  feet.  (Closed  penstock, 
spiral  casing,  horizontal  shaft.  Of  course  for  special  conditions  vertical  shafts 
may  be  used.) 

High  head  turbine,  above  165  feet.  (Closed  penstock,  spiral  casing,  horizontal 
shaft,  as  long  as  reaction  wheels  are  considered;  otherwise,  impulse  wheels  with 
horizontal  or  vertical  shaft.) 

As  this  close  classification  is  seldom  applied  to  American  practice,  a  more  liberal 
classification  must  be  made. 


FIG.  i. — American  Turbine  as  designed  by  the  Dayton  Globe  Iron  Works. 

Low  Head  Turbine.  In  America,  the  low  head  turbine,  a  combination  of  Francis 
and  Jonval  type,  is  manufactured  in  the  horizontal  and  vertical  type,  and  is  known 
as  the  American  turbine.  Frequently  a  number  of  runners  are  mounted  on  a  single 
shaft,  as  seen  in  Fig.  i.  In  many  cases  they  are  placed  in  an  open  flume.  The  runner 

1  Hiitte.     Vol.  I,  p.  802.     Edition,  18. 


MECHANICAL  EQUIPMENT.  131 

of  this  type  of  turbine  was  previously  made  of  steel  buckets  riveted  or  bolted  to  the 
frames.  To-day,  most  manufacturers  make  the  runner  in  one  solid  casting.  Fig.  2 
shows  such  a  runner. 

The  regulating  mechanism  of  the  American  turbine,  as  manufactured  by  the 
Dayton  Globe  Iron  Works,  is  shown  in  Fig.  3.  The  ring  C  which  actuates  the 
guides  D  controlling  the  water  supply  is  governed  through  sector  E.  Other  American 
low  head  turbines  and  application  of  same  will  be  found  throughout  the  text. 


FIG.  2. — Runner  of  "Amer-  FIG.  3. — Crown  Plate  and  Gate 

ican"  Turbine.  of  "American"  Turbine. 

Medium  Head  Turbines.  As  the  line  of  demarcation  between  low  and  medium, 
and  medium  and  high  head,  is  not  distinctly  drawn,  one  will  find  under  this  head  a 
great  variation  of  turbines,  including  high  and  low  head  types.  The  majority  of 
turbines  used  under  medium  head  are  of  the  Francis  type.  It  is  not  the  purpose 
of  this  book  to  go  into  details  of  the  design  of  turbines;  only  the  typical  features 
will  be  given. 

The  Francis  turbines  are  built  in  either  the  horizontal  or  vertical  type,  with  one 
or  more  runners  mounted  on  a  single  shaft.  These  turbines  are  placed,  either 
in  an  open  chamber  of  the  power  house,  or  inclosed  chamber  made  of  cast  iron  or 
structural  steel.  Figs.  5  and  6  show  a  vertical  Francis  turbine  as  built  by  J.  M. 
Voith,  Heidenheim,  Germany,  for  the  Kykkelsrud  plant,  Norway.  It  operates 
under  a  head  of  52.5  feet  to  62.5  feet,  with  a  water  consumption  of  670  to  530  cubic 
feet  per  second,  and  with  150  R.P.M.,  develops  3000- HP.  It  will  be  noticed  that 
the  turbine  casing  is  spiral  in  plan  and  rectangular  in  elevation;  it  is  made  of 
structural  steel.  The  water  enters  the  turbine  casing  with  a  velocity  of  9  feet  per 
second,  and  gradually  increases  to  20  feet,  and  discharges  with  a  velocity  of  3.9  feet 
per  second.  The  runner  has  a  diameter  of  5.9  feet,  and  is  mounted  on  a  1 2-inch 
vertical  shaft,  25  feet  long,  on  the  end  of  which  is  coupled  the  shaft  of  the  generator. 
Between  the  turbine  and  generator  is  a  thrust  bearing,  supplied  with  oil  at  220  pounds 
pressure  per  square  inch,  to  take  up  the  weight  of  the  revolving  element  which  is 
32  tons.  The  water  supply  in  the  turbine  is  controlled  by  clam-shell  gates. 

A  turbine  of  same  make  and  pattern  as  the  above  will  be  found  in  the  plant  of 
the  Ontario  Power  Company,  with  the  exception  that  two  turbines  are  mounted 
upon  a  horizontal  shaft  (see  Fig.  7). 


132  HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 


-a 


c« 

'rt 


CJ 

5 


<a 
W 

o 
t-5 

rj- 

6 


MECHANICAL  EQUIPMENT. 


133 


FIGS.  5  and  6. — Voith  Vertical  Shaft  Francis  Turbine. 


134 


HYDROELECTRIC   DEVELOPMENTS   AND  ENGINEERING. 


FIG.  7. — Plane  and  Elevation  of  Voith  n,34o-HP.  Double  Spiral  Francis  Turbine, 

Ontario  Power  Company. 


MECHANICAL  EQUIPMENT. 


A.E.&M.E 

UNlV.5oF 


FIGS.  8  and  9. — Compound  Francis  Turbine. 


136 


HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 


A  very  interesting  medium  head  turbine  is  installed  at  Wiesberg,  Tyrol,1  and  is 
the  first  of  its  kind  ever  attempted.  As  it  shows  high  efficiencies,  it  bids  fair  to  be 
adopted.  The  reasons  for  adopting  it  are  as  follows:  in  the  above-mentioned  plant 
there  were  installed  three  Francis  turbines  of  1500  HP.  each,  operating  under  a  head 
of  285  feet,  making  300  R.P.M.  During  the  operation,  much  erosion  was  observed, 


[III] 


FIG.  10. — Escher  Wyss  io,ooo-HP.  Turbine  of  the  Niagara  Falls  Power  Company. 

and  the  turbines  lost  their  efficiency  due  to  increase  of  clearance  between  the  runner 
and  the  guides.  As  these  turbines  are  fed  by  glacier  water,  which  in  the  summer 
contains  much  sand,  the  erosion  still  continued  during  the  winter  months,  when 
the  water  is  entirely  free  from  same. 

1  Zweistu6ge  Verbundturbinen  der  Zentrale,  Wiesberg  in  Tyrol,  by  Professor  Pfarr.  Schweitzerische- 
Bauzeitung,  Sept.  14,  1907. 

Prof  Julien  Dalemont  of  the  University  of  Freiburg,  after  making  extensive  investigations  on  the  abnor- 
mal erosion  on  a  number  of  hydraulic  turbines,  operating  under  different  heads  and  with  different  speeds, 
published  his  results  in  a  sixty-page  pamphlet  entitled,  "  L'Eclairage  Electrique,"  Paris.  An  abstract  of  this 
paper,  with  many  illustrations,  is  given  by  Edward  P.  Buffet  in  "Power  and  Engineer"  of  Aug.  4,  1908. 


MECHANICAL  EQUIPMENT. 


137 


The  turbine  built  by  Kolben  &  Co.,  Prague,  Bohemia,  to  overcome  the  effect  of 
erosion,  is  a  compound  turbine  of  the  Francis  spiral  type  as  seen  in  Figs.  8  and  9. 
It  consists  of  two  turbines  mounted  on  the  same  shaft,  so  interconnected  that  the 
discharge  of  one  becomes  the  supply  of  the  other,  thus  reducing  the  head  on  each 
turbine  from  285  to  142.5  feet.  The  spiral  casing  of  each  turbine  is  of  cast  iron  and 
made  in  two  parts  with  an  inlet  of  33.5  inches 
diameter.  Both  runners  are  41.25  inches  in 
diameter  and  of  cast  steel,  and  have  19  vanes. 
With  a  water  consumption  of  88  cubic  feet  per 
second,  the  compound  turbine  developed  2260 
HP.,  making  342  R.P.M.,  giving,  with  a  gate 
opening  of  30,  60  and  90  per  cent,  efficiencies 
of  67,  81  and  86  per  cent  respectively.  After 
the  turbine  had  been  in  operation  one  year,  it 
was  inspected,  and  no  evidence  of  erosion  was 
found;  in  fact,  much  of  the  original  coating  of 
paint  on  the  vanes  was  still  intact. 

As  already  stated,  the  turbines  at  Niagara 
Falls  are  considered  as  medium  turbines.  It 
will  be  observed  that  they  are  located  in  a  pit 
directly  above  the  tailrace.  The  water  enters 
the  cylindrical  turbine  casing  on  the  side  and 
discharges  at  90  degrees  through  2  draft  tubes 
into  the  tailrace.  A  detail  of  the  turbine  installed 
in  the  plant  of  the  Canadian-Niagara  Falls  Power 
Company  is  seen  in  Fig.  10.  It  is  of  the  double 
Francis  type  surrounded  by  a  cylindrical  struc- 
tural steel  casing.  The  runners  are  5.25  feet  in 
diameter.  When  making  250  R.P.M.  under  a 
head  of  131  feet,  with  a  water  consumption  of 
884  cubic  feet  per  second,  the  turbine  develops 
10,000  HP.1 

As  the  turbine  is  set  very  deep  in  the  pit,  the 
shaft  is  made  up  of  three  sections,  at  the  junc- 
tions of  which  are  side  bearings;  the  sections 
themselves  are  partly  made  up  of  steel  pipe.  At 
the  upper  section  is  a  thrust  bearing  (Fig.  u), 
36  inches  in  diameter,  supplied  with  oil  under  a 
pressure  of  367  pounds  per  square  inch.  The 

entire  revolving  element,  including  that  of  the  generator,  weighs  132  tons.  The  weight 
is  also  partly  balanced  by  the  runner  disk,  the  remainder  is  taken  up  by  a  relief 
piston,  3.8  feet  in  diameter. 

1  Schweizerishe-Bauzeitung,  1904.     Vol.  I,  p.  4.     Wagenbach,  Turbinenanlagen,  p.  53. 


FIG.  ii. — Thrust  Bearing  and  Pipe 
Shaft  Connection  of  Niagara  Falls 
Power  Company's  Turbines. 


138 


HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 


High  Head  Turbines.  Among  the  high  head  turbines,  the  Francis  and  impulse 
type  are  the  most  universally  used.  Probably  the  highest  head  developed  is  that 
at  Vouvry  near  Lake  Geneva,  Switzerland,1  where  a  plant  has  been  constructed  for 
a  maximum  capacity  of  20,000  HP.  The  present  equipment  consists  of  four  5oo-HP. 
and  one  2700-!!?.  turbine,  which  operate  under  a  head  of  3116  feet. 

In  America,  of  the  high  head  turbines 
used,  the  impulse  wheel  is  the  most  promi- 
nent; they  are  manufactured  by  several  con- 
cerns, notably  the  Pelton  Water  Wheel 
Company.  This  turbine  is  a  very  simple 
machine;  it  consists  of  a  wheel  with  a  num- 
ber of  buckets  circumferentially  mounted. 
The  wheel  is  usually  mounted  on  a  horizontal 
shaft,  in  some  cases  on  a  vertical;  and  one  or 
more  wheels  mounted  on  a  single  shaft.  The 
water  from  the  penstock  is  directed  against 
the  buckets  through  one  or  more  nozzles  with 
round  openings. 

A  typical  installation  of  a  Pelton  wheel  is 
shown  in  Fig.  13,  as  installed  for  the  Tel- 
luride  Power  Company,  near  Salt  Lake  City, 
Utah.2  The  shaft  of  the  unit  is  mounted 
on  three  bearings,  one  on  each  side  of  the 
generator  and  one  on  the  outside  of  the  wheel. 
The  outboard  generator  bearing,  built  by 
the  Pelton  Water  Wheel  Company,  is  9 
inches  in  diameter,  and  is  of  the  machined 
ball-and-socket  type.  The  bearing  is  in  a 
tight  case  partially  filled  with  oil,  which  is 

carried  up  on  the  shaft  by  loose  rings  riding  on  the  latter,  the  boxing  having  a 
lower  half  only.  Each  water  wheel  is  a  forged  steel  disk,  on  the  periphery  of 
which  are  mounted  24  cast-steel  Pelton  tangential  buckets.  The  wheel  making 
300  R.P.M.  operates  under  an  effective  head  of  1750  feet  at  low  stages  in  the 
reservoir,  and  under  a  maximum  effective  head  of  1775  feet.  Water  is  supplied 
to  each  wheel  through  a  separate  Pelton  needle  deflecting  nozzle.  The  size  of 
the  stream  applied  to  the  buckets  is  hand  regulated,  by  means  of  the  needle  part  of 
the  nozzle,  through  a  standard  mounted  on  a  floor  directly  over  the  rear  end  of  the 
nozzle.  For  changes  in  the  speed  of  the  wheels,  each  nozzle  is  deflected  by  means  of 
a  Pelton  pilot  control  apparatus,  mounted  on  the  floor  in  front  of  the  unit. 

If  it  is  desired  to  throw  the  water  off  the  buckets  in  order  to  shut  down  the  wheel, 
this  may  be  accomplished  by  turning  the  hand  wheel  on  the  control  in  a  counter- 


FIG.  12.— 5000-HP.  Pelton  Wheel. 


1  Wagenbach.     T'urbinenanlagen,  p.  3. 

2  A  Hydro-electric  Development  in  Utah.     The  Engineering  Record,  March  14,  1908. 


MECHANICAL  EQUIPMENT. 


139 


clockwise  direction,  so  that  pressure  is  applied  to  the  top  of  the  piston  in  the  cylinder 
under  the  nozzle  and  released  at  the  bottom. 

The  pair  of  deflecting  nozzles  for  the  two  wheels  are  attached  to  a  Y-connection 
at  the  end  of  the  pressure  pipe  embedded  in  the  mass  of  concrete  under  the  rear  end 
of  the  building.  Each  branch  of  the  Y  is  fitted  with  an  hydraulically  operated  gate 


Pipe  toPr/OfConiro/S+oinol 


FIG.  13. — Pelton  Wheels  installed  for  the  Telluride  Power  Company,  Salt  Lake  City. 

valve,  placed  in  a  covered  pit  in  the  concrete  at  the  rear  of  the  wheel  case.  The 
operation  of  each  of  these  valves  is  controlled  by  a  hand  wheel  mounted  on  a  standard 
on  the  floor  at  the  rear  of  the  unit.  In  order  to  avoid  any  disastrous  effects  from 
water  hammer  in  the  pressure  pipe,  caused  by  a  rapid  closing  of  these  valves,  or  by 
other  conditions,  a  relief  valve  is  placed  in  a  connection  to  the  line  directly  back  of 
the  junction  of  the  branches  of  Y. 

The  discharge  from  the  nozzles,  when  diverted  from  the  buckets,  is  directed 
against  a  curved  baffle  plate  set  in  the  end  of  the  concrete  which  forms  the  pit  under 


140  HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 


FIGS.  14  and  15.— Voith  6ioo-HP.  Spiral  Francis  Turbine.    Hamilton  Cataract  Company. 

the  wheels.  This  baffle  plate  is  arranged  so  that  the  streams  striking  it  tangentially 
are  deflected  90  degrees.  The  stream  is  thus  thrown  into  a  deep  splash  pit,  where  its 
remaining  force  is  absorbed  and  the  water  delivered  to  the  tailrace  practically  quiet. 

As  will  be  seen  from  the  foregoing,  the  Pelton  wheel  is  provided  with  round 
nozzles,  the  regulation  of  which  is  discussed  under  "Governors."     The  European 


MECHANICAL  EQUIPMENT 


141 


impulse  wheel  is  frequently  provided  with  nozzles  of  square  or  rectangular  openings; 
the  construction  of  the  buckets  varies  slightly  according  to  the  nozzle. 

The  wheels  are  mounted  either  on  horizontal  or  vertical  shafts.  As  has  been 
pointed  out,  some  of  the  first  impulse  wheels  constructed  were  mounted  on  a  vertical 
shaft,  similar  to  those  recently  installed  at  the  Necaxa  plant,  Mexico,  which  operate 
under  a  head  of  1300  feet. 

Figs.  14  and  15  show  a  6ioo-HP.  turbine  as  installed  for  the  Hamilton  Cataract 
Company.  It  is  of  the  Francis  spiral  type,  operates  under  a  head  of  261  feet,  making 
286  R.P.M.,  and  has  two  draft  tubes.  The  runner  has  a  diameter  of  4.9  feet.  The 
vanes  are  made  of  phosphor-bronze  and  the  hu^  of  cast  steel.  The  regulation  is 
accomplished  by  an  oil-operated  hydraulic  governor,  which,  in  case  the  load  is 
suddenly  thrown  off,  diverts  part  of  the  water  through  a  by-pass,  then  gradually  shuts 
off  the  supply,  thus  preventing  water  hammer.  Tests  show  that  by  throwing  off 
from  full  load  one-third,  one-half,  two-thirds  of  the  load,  the  speed  varies  i.i,  1.6, 
and  3.5  per  cent  respectively.  Further,  the  turbine  shows  an  efficiency  of  85.8  per 
cent  at  full  gate  and  86.8  per  cent  at  three-quarters  gate. 

Draft  Tubes.  Whenever  possible  turbines  should  be  equipped  with  draft  tubes 
in  order  to  secure  additional  head,  which  would  otherwise  be  lost.  There  are 
instances  where  impulse  wheels  have  been  provided  with  draft  tubes.  However, 
when  so  equipped,  impulse  wheels  run  in  partial  vacuum;  the  water  column  in  the 
draft  tube  must  be  so  regulated  that  it  is  always  a  few  feet  below  the  runner;  there- 
fore near  the  junction  of  the  upper  end  of  the  draft  tube  and  the  turbine  there  must 
be  located  an  air  cock  which  is  controlled  manually  or  by  the  governor.  This 
arrangement  is  preferable  for  small  wheels  and  particularly  where,  owing  to  ground 
water  or  other  reasons,  they  cannot  be  located  near  the  tailrace.  Such  an  installa- 
tion will  be  found  at  Chur.  Switzerland,  where  250-HP.  wheels  operate  under  a 
head  of  272.5  feet.  They  are  provided  with  two  needles.  The  head  gained  by  the 
use  of  the  draft  tube  is  about  15  feet. 

The  theoretical  length  of  a  draft  tube  is  equal  to  perfect  vacuum  or  34  feet. 
Owing  to  losses  due  to  velocity,  friction,  etc.,  in  the  draft  tube,  which  cannot  be 
counteracted,  perfect  vacuum  is  never  realized.  In  practice,  the  height  of  the  water 
in  the  draft  tube  decreases  with  the  increase  of  diameter  of  same  and  vice  versa.  The 
following  table  is  abstracted  from  Meissner  i  and  converted  into  English  units;  the 
dimensions  as  given  are  in  round  numbers. 

TABLE  I. —  HEIGHT  OF  DRAFT  HEADS. 


Diameter  of 
draft  tube  in 
feet. 

Draft  head 
in  feet. 

Diameter  of 
draft  tube 
in  feet. 

Draft  head 
in  feet. 

I 

30.0 

6 

17.0 

2 

3 

27.0 
24.0 

7 
8 

15-5 
14.0 

4 

21-5 

9 

13.0 

5 

19.0 

10 

12.  O 

1  Meissner,  Hydraulische  Motoren,  Vol.  II,  p.  212. 


142 


FIGS.  16  and  17.—  gjoo-HP.  Francis  Turbine,  550  feet  Head,  400  R.P.M.,  for  the 
California  Gas  and  Electric  Corporation.     Allis  Chalmers  Company. 


MECHANICAL  EQUIPMENT.  143 

Draft  tubes  should  always  be  made  conical,  so  as  to  gradually  reduce  the  velocity 
of  discharge,  and  must,  on  the  upper  end,  be  of  the  same  size  as  the  discharge  opening 
in  the  turbine  casing,  to  avoid  any  abrupt  changes  in  the  velocity  of  the  water.  The 
velocity  of  discharge  from  a  draft  tube  should  be  about  2  feet  for  low-head,  3  feet 
for  medium-head,  and  4  to  7  feet  for  high-head  turbines.  Draft  tubes  should  be 
straight  and  free  from  turns  as  possible;  this  is  particularly  true  of  long  draft  tubes. 
The  end  must  be  watersealed,  at  least  some  6  to  12  inches  at  low  water  level  for 
small-sized  tubes,  and  18  to  24  inches  for  large  ones.  Draft  tubes  are  made  of  cast 
iron,  structural  steel,  or  are  part  of  the  concrete  foundations.  When  made  of  metal, 
they  must  be  made  strong  enough  to  stand  atmospheric  pressure  (perfect  vacuum 
is  equivalent  to  a  water  column  34  feet  high  or  a  pressure  of  14.7  pounds  per  square 
inch)  and  any  pulsations  which  might  arise  by  starting  and  running  turbine  under 
great  variations  of  load;  for  the  latter  reasons  a  long  draft  tube  must  be  properly 
anchored. 

REGULATING    DEVICES. 

Principle  of  Governors.  Turbines  and  water  wheels  in  general,  coupled  to 
generators,  must  be  provided  with  governors  of  proper  design,  to  regulate  same 
so  that  the  speed  will  be  nearly  constant.  The  irregulation  in  a  hydroelectric 
plant  may  have  its  origin  in  the  hydraulic  end,  such  as  water  hammer  and  surging 
in  the  penstock  or  draft  tube,  loss  of  vacuum  in  draft  tube,  etc.;  in  the  mechanical 
end,  poor  operation  of  the  turbine  and  the  supply  gates,  controlling  of  waste  water 
in  case  of  a  sudden  shut  down,  which  might  arise  from  the  hydraulic,  mechanical, 
or  electrical  end  of  the  station. 

There  are,  of  course,  other  factors  which  necessitate  the  choosing  of  a  governor 
adaptable  to  control  load  fluctuation  for  the  particular  plant;  for  instance,  successful 
operation  of  a  high-head  plant  may  be  accomplished  either  by  quick-acting  or  slow- 
acting  governors.  Where  the  load  on  a  plant  is  steady,  a  slow-acting  governor 
gives  best  results.  In  addition  to  a  governor  the  turbine  may  be  provided  with  a 
special  fly  wheel.  The  runner  of  the  turbine,  or  the  field  magnet  of  the  generator,  is 
designed  to  serve  the  same  purpose,  that  is,  preventing  water  hammer  in  the  penstocks 
and  other  irregularities  in  operation.  A  plant  with  great  load  fluctuation  is  best 
regulated  by  a  quick-acting  governor;  but  a  governor  of  this  kind  must  be  provided 
with  auxiliaries  to  by-pass  the  water  into  the  tailrace,  as  otherwise  the  sudden  cut-off 
of  a  moving  column  of  water  will  set  up  violent  surges  and  liability  of  damage  to 
governor  as  well  as  the  penstock.  As  this  by-pass  water  is  always  wasted,  a 
governor  should  be  designed  to  close  soon  after  the  turbine  is  cut  off.  A  type  of 
such  a  governor  is  seen  in  Fig.  i.  This  turbine  is  of  the  impulse  type  as  installed 
in  the  Brusio  plant.  As  will  be  seen,  the  nozzle  is  stationary,  while  the  needle  is 
moved  forward  and  back  by  a  piston  controlled  by  the  governor,  which  also  actuates 
the  by-pass  located  in  the  continuation  of  the  penstock. 

The  regulation  acts  as  follows:  when  the  water  to  the  wheel  is  cut  off  by  the  needle 
the  by-pass  opens  at  the  same  time  and  closes  gradually,  so  that  only  little  water  is 
wasted;  the  main  valve  closes  simultaneously  with  the  closing  of  the  by-pass. 


144 


HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 


Small  fluctuations  are  taken  up  by  the  needle  and  by-pass.  The  main  valve  serves 
as  relay.  The  duration  of  closing  is  set  by  a  hand  wheel  on  the  governor.  Tests 
show  that  by  suddenly  throwing  off  full  load  the  speed  variation  is  10  per  cent. 

Another  type  of  Swiss  governor  is  shown  in  Fig.  2,  as  installed  in  connection 
with  a  25OO-HP.  high-pressure  turbine  of  the  so-called  "  Spoon  Wheel"  type,  operating 
under  a  head  of  1023  feet,  at  Lucerne,  Switzerland.  The  governor  is  operated  by 


FIG.  i. — Escher  Wyss  Impulse  Wheel  with  Non-Water-Wasting  Nozzle  and  Regulator. 

means  of  gearing  from  the  main  shaft,  and  adjusts  the  opening  of  the  jet  by  means 
of  an  oil-actuated  piston  device. 

The  nozzle  opening  is  6  by  3.5  inches  and  is  varied  by  a  hinged  jaw.  The 
opening  and  closing  action  of  the  by-pass  takes  place  simultaneously  with  that  of  the 
nozzle.  Similar  to  that  in  the  former  mentioned  device,  the  water  is  by-passed  for 
only  a  short  time  before  the  main  valve  closes  (see  Fig.  3),  which  is  automatically 
controlled.  The  closing  this  main  valve  can  be  regulated  to  20  seconds,  while  the 


MECHANICAL    EQUIPMENT. 


145 


S 
Jl 

c 


c 
'H 

rt 


3 

H 


146 


HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 


action  of  the  governor,  by  throwing  off  full  load  (2500  HP.),  requires  2  to  2.5  seconds, 
giving  after  6  seconds  a  speed  regulation  of  4  per  cent.  The  governor  is  provided 
with  several  indicators,  one  of  which  gives  in  per  cent  the  nozzle  opening  and  one 
the  by-pass  opening. 


FIG.  3. — Automatic  Main  Turbine  Gate. 

Lombard  Governor.  The  illustration,  Fig.  4,  shows  a  type  of  oil-pressure  gov- 
ernors as  manufactured  by  the  Lombard  Governor  Company  of  Ashland,  Mass. 
This  governor  consists  essentially  of  three  parts  —  the  oil  pump,  the  pressure  and 
vacuum  tanks,  and  the  governing  mechanism. 

The  centrifugal  head  shown  distinctly  at  the  upper  right  of  illustration  is  belted 
directly  to  the  turbine  shaft.  It  controls  a  primary  valve  immediately  below  it. 
The  oil,  normally  under  200  pounds  pressure,  which  is  received  from  the  pressure 
tank,  is  allowed  to  enter  a  vertical  10  inch  by  24  inch  cylinder  through  an  inter- 
mediate piston  valve,  which  is  controlled  by  the  primary  valve  and  a  system  of 


MECHANICAL  EQUIPMENT. 


147 


unbalanced  pressures.  The  oil  exhausts  from  the  cylinder  through  the  same  inter- 
mediate valve  into  the  receiving  tank.  The  pressure  and  vacuum  are  created  by 
the  pump,  which  can  be  either  motor  driven  or  belted  to  the  turbine  shaft.  The 
motion  from  the  piston  rod  to  the  gate  mechanism  of  the  turbine  is  transmitted  by 
means  of  racks  and  gears. 

A  simple  and  effective  anti-racing  mechanism  is  used,  whereby  the  action  of  the 
governor,  however  rapid,  ranging  from  one  to  four  seconds  for  full  stroke  of  the 
piston,  is  rendered  dead-beat. 


FIG.  4. — Lombard  Governor. 

A  Lombard  hydraulic  relief  valve  is  seen  in  Fig.  5.  It  is  connected  to  the  penstock 
near  the  turbine,  and  can  be  set  for  any  excess  pressure  desired;  it  is  claimed  that  it 
will  operate  on  an  excess  pressure  of  one  per  cent. 

Glocker-White  Governor.  This  governor  as  manufactured  by  the  I.  P.  Morris 
Company  is  seen  in  Fig.  6.  One  essential  feature  is  the  governor's  centrifugal 
weights  in  the  form  of  a  boot,  partially  filled  with  mercury,  which,  when  running 
at  normal  speed,  is  divided  between  two  chambers.  With  an  increase  of  speed  the 
centrifugal  force  causes  the  mercury  to  flow  from  the  lower  to  the  upper  chamber; 
thus  the  center  of  gravity  increases  in  a  greater  ratio  than  the  speed,  and  vice  versa. 
The  action  is  transmitted  through  a  system  of  levers  to  a  small  pilot  valve  controlling 
a  relay  valve,  admitting  oil,  under  250  pounds  pressure,  to  the  cylinder,  which  in 
turn  actuates  the  turbine  gates. 


148 


HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 


Replogle  Governor.  The  Replogle  governor  l  is  purely  mechanical  in  operation, 
the  principle  of  which  is  given  below. 

"In  the  diagram  (Fig.  7),  A  is  a  spherical  pulley  with  its  shaft  turned  down 
and  threaded  as  at  X.  B  and  B  are  oppositely  revolving  concave  disks  lined  with 
leather.  C  and  C  are  lignum-vitae  pins  flush  with  the  leather.  D  and  D  are  com- 


FIG.  5. — Lombard  Hydraulic  Relief  Valve. 


pression  springs  for  causing  the  necessary  pressure  between  the  disks  and  the  sphere. 
E  and  E  are  governor  balls  so  poised  as  to  require  the  weight  of  A  to  balance  them  at 
normal  speed.  F  is  a  loose  collar  to  allow  independent  revolution  of  the  balls  E,  E. 
G  is  the  point  of  connection  between  A  and  the  gates  or  valves  of  the  motor  to  be 
governed.  X  is  the  relay  device,  and  is  for  the  purpose  of  preventing  racing,  also 
for  the  purpose  of  properly  dividing  the  load  in  parallel  units.  Z  is  a  stationary 
spindle  or  connecting  link  between  collar  F  and  the  threaded  shaft  or  pulley  A. 

1  Some  Stepping  Stones  in  the  Development  of  a  Modern  Water- Wheel  Governor,  by  Mark  A.  Replogle. 
A.  S.  M.  E.,  Chattanooga,  Tenn.,  May,  1906. 


MECHANICAL  EQUIPMENT. 


149 


Z  is  only  stationary  in  reference  to  revolution,  as  it  rises  or  falls  with  the  variations 
of  the  governor  balls. 

"  The  following  is  a  description  of  the  governor's  action  if  the  speed  should  drop 
by  an  addition  of  load,  the  lessening  of  the  centrifugal  effects  on  E,  E  will  allow  A 
to  drop  below  the  centers  of  disks  B,  B,  which  are  constantly  revolving  in  the  direc- 
tion shown  in  the  diagram.  As  soon  as  A  falls  below  the  disk  centers,  it  will  begin 


FIG.  6. — Glocker-White  Governor  (I.  P.  Morris  Company). 

to  revolve  slowly  to  the  right,  being  the  direction  that  will  turn  on  power.  While 
A  is  turning  to  the  right  it  shortens  the  distance  to  collar  F  by  means  of  the  thread  at 
X.  This  shortening  causes  A  to  be  pulled  back  to  the  disk  centers,  thereby  cutting 
the  governor  out  of  action.  It  will  be  noticed  that  E  and  E  have  not  shifted  their 


HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 


>r  Ban 


JU..\.KeptoyU 


FIG.  7. — Replogle  Governor. 


FIG.  8.— Pressure  Regulator  (Bell  &  Co.). 


MECHANICAL  EQUIPMENT. 


A.E.&M, 


UN'IV.  OF  CA 

position  during  the  act  of  opening  the  valves.  Therefore  the  speed  is  in  reality- 
lower  after  the  new  power  is  added  than  it  was  before  the  change  in  load.  It  is  now 
clear  that  there  is  a  continuous  dropping  in  the  speed  while  the  valves  are  opening. 
In  practice  this  permanent  drop  is  enough  to  insure  the  correct  division  of  load. 
It  is  also  enough  to  permit  of  successful  government  where  adequate  power  storage 
exists  in  the  unit  to  be  governed.  In  this  governor  there  is  no  special  provision  for 
temporary  relay.  Such  provision  is  unnecessary  except  where  the  momentum 
effects  are  small.  (In  the  governor  shown  the  permanent  drop  can  be  varied  by  the 
pitch  of  the  thread  used  at  X.)  In  ordinary  practice  it  is  about  2  per  cent." 

Pelton  Nozzle  Regulation.  The  usual  method  of  controlling  the  speed  of  the 
Pelton  wheel  is  by  means  of  a  deflecting  nozzle,  needle  nozzle,  or  a  combination  of 
both.  Which  one  of  these  types  is  most  suitable  depends  on  the  condition  of  the  head, 
power  and  character  of  load. 

The  deflecting  nozzle  is  a  cast-iron  nozzle  provided  with  a  ball  and  socket  joint, 
permitting  of  its  being  raised  or  lowered,  thus  throwing  the  stream  on  or  off  the 
buckets.  The  power  of  the  wheel  is  consequently  increased  or  diminished,  according 
to  the  change  of  load,  and  a  constant  speed  is  maintained.  A  steel  deflecting  plate, 
which  deflects  the  stream  itself,  the  nozzle  remaining  stationary,  is  sometimes  used 
to  accomplish  the  same  results  when  the  design  will  not  admit  of  a  deflecting  nozzle. 


FIG.  9. — Instantaneous  photograph  of  Tangential  Wheel  fitted  with  Pelton  Buckets  when 
running  at  high  efficiency,  showing  the  discharge  from  the  sides  of  the  buckets  parallel 
with  the  entering  jet;  the  photograph  also  shows  clearly  that  the  front  of  the  Pelton  Bucket 
enters  the  stream  without  shock  or  disturbance  of  any  kind  and  that  all  of  the  energy  is 
removed  from  the  water  by  the  bucket. 


The  needle  nozzle  consists  of  a  nozzle  body  in  which  is  inserted  a  concentric 
tapered  needle.  A  change  of  position  of  this  needle  produces  a  corresponding 
change  of  discharge  area  of  the  nozzle.  The  amount  of  water  used  is  thus  varied  and 
the  power  of  the  wheel  influenced  proportionately. 

The  needle  and  deflecting  nozzle  is  a  most  valuable  combination*,  consisting  of  a 
deflecting  nozzle,  with  which  is  incorporated  a  needle  nozzle  with  means  for  operating 


152 


HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 


either  the  needle  or  deflecting  nozzle  simultaneously  or  separately.  The  deflecting 
nozzle  in  itself  is  a  most  sensitive  means  of  regulation  when  actuated  by  an  auto- 
matic governor,  but  does  not  save  water.  On  the  other  hand,  the  needle  nozzle, 
while  it  is  extremely  economical  in  the  use  of  water,  is  difficult  to  control  quickly  by 
means  of  the  governor.  The  operation  of  the  combination  is  as  follows: 

Assuming  the  full  load  to  be  on  the  water  wheel,  and  the  nozzle  in  position  of 
greatest  efficiency,  a  decrease  of  load  will  cause  the  nozzle  to  be  suddenly  deflected 
by  the  automatic  governor.  Simultaneously  the  needle  portion  of  the  nozzle  will 
be  actuated  by  hand,  or  by  another  automatic  device,  tending  to  gradually  close 
the  needle  and  decrease  the  flow.  The  governor  then  raises  the  nozzle  to  accommodate 
the  decreased  flow  of  water  (and  consequent  decrease  of  power),  and  the  nozzle  is 
then  brought  back  to  the  position  of  greatest  efficiency,  having,  at  the  same  time, 


FIG.  10. — Automatic  Needle  and  Deflecting  Nozzle,  Pelton  Impulse  Wheel. 

controlled  the  speed  within  the  required  limits.  Such  a  device  is  essential  where 
water  is  valuable  and  where  economy  is  necessary  to  carry  over  the  peak  load. 
The  needle  portion  need  not  necessarily  be  operated  by  an  automatic  device,  but 
may  be  controlled  by  hand,  and  the  same  results  obtained,  although  necessarily  in 
a  longer  period  of  time.  An  installation  of  this  combination  is  given  in  Fig.  10. 

The  lower  end  of  penstocks,  particularly  of  high-head  plants,  must  be  provided 
with  reb'ef  valves,  as  already  discussed  under  penstocks.  Fig.  n  shows  a  battery  of 
relief  valves  as  employed  by  the  Pelton  Water  Wheel  Company  in  connection  with 
their  impulse  wheels.  They  may  be  installed  either  singly  or  in  a  battery,  which 
depends  on  the  size  of  the  penstock  and  the  working  head.  These  valves  are  set  to 
operate  at  a  pressure  slightly  greater  than  the  normal,  and  in  the  event  of  the  water 
flow  being  suddenly  checked  by  the  closing  of  the  gate  or  operation  of  the  governors 
the  safety  valves  momentarily  open  and  relieve  the  pressure,  thus  guarding  the 
penstock  against  the  possibility  of  water  hammer. 

Accessories.  For  operating  hydraulic  governors  either  by  water  or  oil  pressure, 
additional  auxiliaries  such  as  oil  pumps,  pressure  accumulators,  and  water  filters 


MECHANICAL  EQUIPMENT. 


153 


are  necessary.  Particular  care  must  be  taken,  if  the  penstock  water  is  used  in 
hydraulic  governors,  to  clean  same,  which  is  done  by  sending  the  water  through  a 
screen  chamber.  There  must  be  at  least  two  screens,  so  that  one  may  be  in  use 
when  the  other  is  being  cleaned. 

The  pressure  oil  for  the  relays  or  pilot  valves  of  the  governors  is  usually  supplied 
by  motor-driven  plunger  pumps.  As  this  oil  is  also  used  in  the  step  and  thrust 
bearings  and  frequently  must  be  under  high  pressure,  the  pressure  to  the  governor 


FIG.  ii.— Battery  of  Relief 
Valves. 


FIG.  12. — Combination  of  Fly- Wheel  and 
Flexible  Leather  Link  Coupling. 


must  be  lowered  by  reducing  valves.  To  insure  continuity  of  operation  two  or 
more  pumps  must  be  installed.  In  connection  with  these,  accumulators  are  installed 
to  take  up  fluctuations  in  the  pressure. 

Couplings.  The  turbines  may  be  rigidly  or  flexibly  coupled  to  the  generators. 
The  rigid  coupling  is  used  where  there  is  little  fluctuation  on  either  the  hydraulic 
or  the  electrical  end  of  the  plant.  The  flexible  couplings  serve  two  purposes:  first, 
to  take  up  light  speed  variations;  second,  in  most  cases  it  insulates  the  turbine  from 
the  generator,  as  the  actual  connection  between  the  turbine  and  generator  is  done 
by  means  of  leather  or  rubber.  A  coupling  very  much  used  in  Switzerland  is  the 
Zodel.  It  consists  of  two  concentric  cylindrical  flanges  provided  with  slots,  through 
which  a  belt  is  wound  in  and  out.  Frequently  these  couplings  are  so  designed  as 
to  act  as  a  fly  wheel  to  balance  fluctuations  of  load.  A  coupling  designed  on  this 
principle  is  shown  in  Fig.  12. 


154 


HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 


OILING    SYSTEM. 

Oil  Required.  It  is  of  vital  importance  to  install  an  oiling  system  in  all  power 
plants,  large  as  well  as  small.  A  complete  oiling  system  collects  the  oil  from  the 
bearings,  filters  it  and  returns  it  to  the  machine,  all  of  which  is  done  automatically. 
From  50  to  70  per  cent  of  oil  used  in  power  plants  is  wasted  if  means  are  not 
provided  to  collect  same. 

Filtering  Tanks.  The  filtering  tank  must  be  so  located  that  the  oil  will  flow  to 
it  by  gravity.  The  tanks  must  be  installed  in  a  fireproof  compartment.  This 


AUTOMATIC 
WATER 

SEPARATING! 

APPARATUS 


TO  SEWER 


FIG.  i.— Burt  Oil  Filter. 


compartment  may  also  contain  the  oil  pumps  as  well  as  the  waste  cleaner  and  drier. 
The  door  must  be  so  arranged  that  it  will  shut  automatically.  If  the  room  is  large, 
it  is  better  to  install  two  doors,  one  as  a  means  of  easy  escape  for  the  attendant. 
The  floor  must  be  provided  with  proper  drainage,  as  it  is  frequently  necessary  to 
clean  the  tanks  and  filters. 

Many  of  the  larger  power  plants  have  filtering  tanks  of  special  design,  but 
common  practice  is  to  install  some  regularly  manufactured  article.  The  tanks 
must  be  in  duplicate,  or  so  arranged  in  compartments  that  one  may  be  cleaned  at 


MECHANICAL  EQUIPMENT. 


155 


a  time  without  putting  the  entire  tank  out  of  service.  Large  tanks  may  be  con- 
structed of  many  compartments.  The  oil,  entering  through  cheese  cloth  or  light 
canvas  filters,  passes  through  the  compartments  at  a  low  velocity,  precipitating  any 
foreign  substances. 


Section.  1         {Action  2       Section    3        Section  4 


FIG.  2.— Turner  Oil  Filter. 


4  Suction  Bj  Pal. 


OOOOOOO 
OOOOOOO 

ooooooo 

OOOOOOO 
OOOOOOO 

oooo&oo 

OOOOX3OO 


OOOOOOO 

ooooooo 
0006000 
ooo@ooo 

OOOOOOO 


Cf&O  O  O  O  O  ilTO  O  O  O  O 

on'ooooo  irooooooo 


fuuuuuuu  uuuuuuu  uuuuuuin 


FIG.  3. — Oil  Filtering  Tank  for  Large  Capacities. 

The  filtering  tanks  may  have  a  heating  coil  to  heat  the  oil,  thereby  increasing  the 
speed  of  filtration  and  causing  more  rapid  precipitation.  When,  however,  high 
speed  turbines  are  used,  and  the  temperature  of  the  oil  returned  to  the  filters  is  high, 
the  use  of  the  coil  may  be  dispensed  with. 


156  HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 

Very  frequently  the  oil  returned  contains  a  certain  amount  of  water.  It  is  important 
to  abstract  this  water.  Fig.  i  shows  a  typical  oil  filter  of  this  type  as  manufactured 
by  the  Burt  Manufacturing  Company.  The  oil  entering  at  the  top  passes  through 
the  waste  contained  in  the  center  chamber,  from  where  it  passes  downward  through 
the  pipe  C,  is  heated  by  the  coil  and  flows  upward  through  the  water  contained  in  the 
lower  portion  of  the  tank.  This  water  forces  the  oil  through  the  waste  F  into  the 
pure  oil  compartment,  from  which  it  is  drawn  off  and  reused.  The  water  is  dis- 
charged to  the  sewer  through  the  automatic  water  separator,  shown  on  the  left-hand 
side  of  the  cut. 

Another  very  efficient  oil  filter  is  shown  in  Fig.  2,  representing  the  Turner 
system.  As  will  be  seen,  this  tank  is  divided  up  into  four  sections.  The  oil  passes 
through  the  filtering  material  of  each  section,  having  its  temperature  raised  by  coils 
in  the  first  two  sections.  A  very  efficient  oil  filtering  tank  is  shown  in  Fig.  3.  The 
tank  is  divided  into  chambers  by  partition  walls  extending  alternately  to  the  top 
and  bottom  of  the  tank,  giving  the  oil  an  up  and  down  flow,  thus  increasing  precipi- 
tation, which  will  be  greater  the  lower  the  velocity.  The  oil  before  entering  the 
tank  passes  through  Canton  flannel  bags,  arranged  in  trays  as  shown  in  the  illus- 
tration. These  bags  are  removable,  and  when  dirty,  may  be  replaced  by  clean  ones. 
The  pipe  connections  are  such  that  any  chamber  may  be  separately  cleaned  without 
shutting  down  the  entire  filter. 

Oil  Pumps.  The  pumps  required  for  an  oiling  system  are  either  high  or  low 
pressure.  The  latter  are  used  with  a  central  oiling  system.  Duplicate  pumps  must 
be  installed  in  order  to  keep  one  in  reserve.  With  certain  turbines  high-pressure 
pumps  are  required  to  pump  the  oil  into  the  step  bearing.  It  is  better  practice  to 
install  several  small-size  pumps  than  one  or  two  large  ones,  as  the  possibility  of 
shut-down  is  thereby  lessened.  With  the  vertical  turbine  in  some  instances  water 
is  used  for  the  step  bearing,  with  practically  the  same  results  as  those  obtained  with 
the  use  of  oil.  The  entire  equipment,  with  the  exception  of  the  filtering  tanks,  is 
the  same  as  the  oiling  system. 

Supply  Tanks.  Frequently  it  is  necessary  to  install  one  or  two  elevated  supply 
tanks,  from  which  the  oil  is  fed  by  gravity  to  the  various  bearings.  These  tanks 
must  be  properly  vented,  and  where  more  than  one  tank  is  employed,  they  must 
be  interconnected.  In  order  to  avoid  complicated  and  long  pipe  mains,  these  tanks 
are  preferably  placed  somewhere  in  the  center  of  the  plant.  As  the  oil  is  used  over 
and  over  again,  and  its  temperature  is  increased  each  time  it  is  used  (especially  with 
high-speed  turbines),  it  might  be  necessary  to  cool  the  oil  by  means  of  water  coils 
placed  in  the  supply  tank,  before  it  returns  to  the  bearings. 

Oil  Piping.  The  return  pipes  leading  the  oil  from  the  various  bearings  or 
collecting  pans  to  the  filtering  tank  may  be  of  either  wrought  or  cast  iron.  The  former 
is  preferable,  however,  for  small  pipes.  If  wrought  iron  is  employed  screw  fittings 
may  be  used.  In  order  to  secure  a  good  gravity  flow  for  the  oil  the  pipes  should 
be  pitched  at  least  one  inch  in  every  ten  feet. 

Where  many  returns  are  connected  to  one  common  header,  provision  has  to  be 
made  for  the  removal  of  air.  This  is  accomplished  by  placing  one-half  inch  or 


MECHANICAL  EQUIPMENT.  157 

three-quarter  inch  vent  pipes  on  the  header.  These  vents  must  extend  above  the 
highest  point  in  the  return  piping,  so  that,  if  the  pipe  discharging  to  the  filter  becomes 
plugged,  the  oil  will  not  escape  through  the  vents.  To  facilitate  cleaning  the  pipe, 
it  is  good  practice  to  install  crosses  instead  of  tees  in  the  header,  one  leg  being  plugged. 
The  supply  pipes  from  the  filter  to  the  elevated  tank,  and  also  the  pipe  from  the  tank 
to  the  machines,  must  preferably  be  made  of  brass  or  copper.  This  is  absolutely 
necessary,  as  steel,  wrought-iron,  or  cast-iron  pipe  contains  a  scale  which  oil  loosens, 
and  if  this  scale  gets  into  the  bearings  it  is  liable  to  cause  considerable  damage. 
Galvanized  iron  pipe  has  been  tried  for  supply  piping,  but  experience  has  shown 
that  the  galvanizing  will  wear  off  and  the  pipe  will  scale  as  badly  as  a  black 
iron  pipe. 

It  is  essential  to  keep  the  pressure  constant  in  high-pressure  oiling  systems. 
This  may  be  accomplished  by  accumulators. 

TESTING    TURBINES. 

European  Methods.  It  is  difficult  to  keep  the  load  and  revolutions  of  a  turbine 
steady  for  long  periods,  to  secure  data  for  figuring  the  exact  water  consumption. 
It  is  therefore  essential  to  devise  a  system  whereby  the  flow  of  water  is  indicated 
simultaneously  with  the  load  and  revolution  of  the  turbine.  This  is  best  accomplished 
by  automatic  graphical  methods,  registering  the  load,  revolutions,  water  levels  in 
head  and  tail  race,  water  discharged,  and  time.  A  device  of  this  kind  (Reichel  and 
Fuess  system)  is  seen  in  Fig.  i.  It  has  been  used  for  some  years  in  Germany, 
and  consists  of  a  vertically  revolving  drum,  with  six  different  recording  indicators 
for  the  different  readings.  The  drum,  by  means  of  worms  and  gears,  is  actuated  by 
a  220  V.  £\f  HP.  motor,  making  2750  R.P.M.,  and  the  speed  of  the  drum  can  be 
varied  at  will  between  0.6  mm.  and  15  mm.  per  second.  The  drum  itself  can  be  set 
in  four  different  positions  on  the  vertical  shaft,  so  that  four  complete  tests  can  be 
recorded  on  the  same  sheet. 

It  will  be  observed  that  there  is  a  clock  connected  with  the  recording  mechanism, 
cutting  in  and  out  the  four  relays  for  the  four  lower  indicators.  The  two  upper 
indicators  are  attached  to  the  wires  running  to  the  floats,  one  for  the  headrace  and  the 
other  for  the  tailrace. 

The  load  on  the  turbine  is  measured  by  a  Prony  brake,  and  indicated  on  the 
recording  device.  The  discharge  of  the  tailrace,  measured  by  current  meters,  is  also 
recorded. 

It  is  usually  difficult  to  measure  the  exact  discharge  of  the  tailrace,  as  it  varies 
greatly  according  to  the  proximity  of  the  channel  walls,  and,  as  an  exact  average  flow 
throughout  the  channel  can  hardly  be  ascertained,  because  a  constant  turbine  load  is 
only  of  short  duration,  therefore  it  is  well  to  install  a  number  of  current  meters. 
This  may  be  done  by  having  three  or  five  meters,  according  to  the  depth  of  the  tail- 
race  channel,  on  a  vertical  shaft  secured  to  a  carriage,  which  is  moved  across  the 
channel  to  four  or  six  points,  depending  on  the  width  of  same. 

The  carriage  must  move  easily,  the  rollers  resting  on  an  I-beam  or  channel  iron, 


158 


HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 


so  that  successive  measurements  can  be  taken  very  rapidly  by  running  the  carriage 
along  to  different  points.  Practice  shows  that  by  having  three  current  meters  on 
one  shaft,  and  moving  the  carriage  in  five  different  positions,  fifteen  readings  of  the 
tailrace  cross  section  can  be  made  in  five  minutes. 

For  measuring  the  discharge  of  the  turbine  in  a  simpler  and  perhaps  the  most 
accurate  way,  a  method  has  been  long  in  vogue  in  Norway  and  Sweden  and  recently 


FIG.  i. — Automatic,  Graphical  Registrator  for  Testing  Turbines. 


introduced  into  Germany.  It  was  developed  by  Prof.  Erik  Anderson,  Stockholm. 
To  make  use  of  this  method,  the  tailrace  must  be  some  30  feet  to  40  feet  long  and 
have  a  uniform  cross  section  with  smooth  surfaces.  A  carriage,  preferably  made  of 
aluminum  or  light  steel  bicycle  tubes,  rests  on  a  smooth  track,  preferably  on  the 
planed  legs  of  angle  iron.  To  the  carriage  is  hinged  a  light  framework  of  wood  or 
steel,  of  the  width  of  the  tailrace,  giving  on  each  side  a  clearance  of  about  a  quarter 


MECHANICAL  EQUIPMENT. 


159 


to  three-eighths  of  an  inch.  This  frame  is  covered  with  oiled  cloth  or  other  water- 
proof canvas.  The  total  weight  of  those  as  illustrated  in  Fig.  2  is  about  80  pounds, 
and  takes  about  0.8  pound  to  move  same. 

Fig.  3  shows  the  general  arrangement  of  a  testing  plant  at  Heidenheim.  At 
point  /  the  curtain  is  lowered  and  soon  assumes  a  vertical  position  before  entering 
the  area  of  measurement.  Point  ///  shows  the  carriage  in  a  position,  with  the 


FIG.  2. — Carriage  with  Curtain  for  Testing  the  Water  Discharge  of  Turbines. 


FIG.  3. — Arrangement  for  Measuring  Tailrace  Water  in  Testing  Turbine  by  the  Curtain 

Method. 

curtain  released  from  the  vertical  position  by  means  of  a  trip  device;  the  carriage  is 
then  drawn  back  for  another  run.  Practice  shows  that  every  four  minutes  a  com- 
plete test  can  be  recorded.  The  speed  of  movement  depends  on  the  exact  uniform 
water  velocity  throughout  the  tailrace  channel.  It  must  here  be  stated  that  with  a 
water  velocity  of  less  than  0.5  foot  per  second  the  measurements  become  inaccurate. 
The  position  and  time  of  travel  are  recorded  by  electrical  contacts  placed  some  three 
to  five  feet  apart. 


i6o 


HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 


The  difference  in  the  water  level  at  both  ends  of  the  tailrace  varies  between 
one  and  two  millimeters;  the  average  is  taken  as  final.  Such  tests  are  not  made  on 
windy  days,  because  the  outside  water  is  swept  into  the  tailrace,  and  the  force  of 
same  is  oftentimes  sufficient  to  reverse  a  current  meter. 


FIGS.  4  and  5. — Plan  and  Section  of  Holyoke  Testing  Flume,  showing  Turbine  in 

Position  for  Test. 

Holyoke  Tests.  Most  of  the  low-head  turbines  manufactured  in  America  are 
tested  at  the  flume  of  the  Holyoke  Water  Power  Company,  Holyoke,  Mass.  As  the 
head  on  this  plant  is  only  18  feet,  and  is  seldom  constant,  due  to  great  fluctuations, 
all  the  readings  therefore  have  to  be  reduced  to  a  uniform  head.  Further,  as  the 


MECHANICAL  EQUIPMENT. 


161 


conditions  of  the  flume  and  the  setting  of  the  wheel  are  different  from  those  at  the 
plant  where  the  wheel  is  to  be  installed,  the  value  of  the  Holyoke  tests  may  be 
judged  from  the  following  comparison. 

Due  to  the  high  efficiency  claims  of  some  American  manufacturer,  a  German 
concern  intended  to  build  turbines  after  the  American  type,  for  which  purpose  it 
bought  a  i6-inch  turbine,  duly  tested  at  Holyoke,  then  tested  in  Germany  by  Professor 
Pfarr,  one  of  the  highest  German  authorities  on  turbines.  The  results  of  these  tests 
are  published  in  the  ZeUschrift  des  Vereines  deutcher  Ingenieure,  June  7,  1902.  The 
comparison  of  the  efficiencies  is  as  follows: 


Discharge  

I.  O 

o.  o 

0.8 

O.  7 

0.6 

o.  t; 

O    4. 

O    1 

Holyoke  test  

0.81 

0.  70? 

o.  76? 

o.  72? 

o.  67 

German  test  

0.718 

0.703 

o  693 

0.658 

0.591 

0.491 

0-358 

O.  121 

The  discharge  is  the  actual  discharge  and  is  not  figured  on  the  proportional  gate 
opening.  During  the  Holyoke  tests  the  total  weight  on  the  step  bearing  was  25  per 
cent  greater  than  that  in  the  German  tests. 

For  these  reasons,  guarantees  of  such  tests  must  not  be  accepted  by  the  power 
plant  designer;  he  should  accept  only  such  guarantees  as  are  made  in  the  power  plant 
itself. 

However,  as  the  Holyoke  tests  are  used  in  many  respects  as  a  standard  in 
American  practice,  a  brief  description  of  the  Holyoke  Test  Flume  method  of 
testing  and  deduction  as  given  by  the  Dayton  Globe  Iron  Works  Company  is 
given  below. 

For  the  purpose  of  making  the  necessary  experiments  on  the  wheels,  the  Holyoke  Water  Power 
Company  built  a  permanent  testing  flume,  in  which  the  wheels  are  tested  both  for  power  and  for 
amount  of  water  discharged.  They  are  usually  tested  at  five  or  six  different  openings  of  the  gate, 
ranging  from  full  open  to  the  opening  at  which  the  discharge  is  one-half  that  at  full  opening, 
and  at  six  or  eight  different  velocities  of  revolution  at  each  gate  opening,  and  making  some 
thirty  to  fifty  experiments  on  each  wheel.  The  final  result  is  that  for  all  practical  purposes  the 
water  wheel  is  converted  into  a  water  meter,  and  its  discharge  may  be  known  under  any  of  the 
conditions  under  which  it  will  have  to  run.  Besides  this,  its  efficiency  or  value  as  a  motor  is 
also  known. 

The  essential  portion  of  the  testing  flume  consists,  in  the  main,  of  the  trunk  or  penstock  M,  bring- 
ing the  water  into  the  wheelpit  D  and  the  tailrace  E.  In  the  passageway  M  are  placed  two  sets  of 
racks,  or  baffleboards,  to  stop  eddies  and  oscillations  in  the  flowing  water.  Baffleboards  are  also 
placed  in  the  tailrace  for  the  same  purpose  Flume  wheels  are  set  in  the  center  of  the  floor  of  D,  and  D 
is  filled  with  water.  They  discharge  through  the  floor  of  D  and  out  of  the  three  culverts  N,  N,  N  into 
the  tailrace  E.  At  the  downstream  end  of  this  tailrace  is  the  measuring  weir  O,  the  crest  being 
formed  of  a  piece  of  planed  wrought  iron.  It  can  be  used  with  or  without  end  contractions.  The 
depth  of  water  on  the  weir  is  measured  by  a  hook  gauge,  in  a  cylinder  P,  set  in  a  recess  Q  fashioned 
into  the  sides  of  the  tailrace.  These  recesses  are  water  tight,  and  the  observer  is  thus  enabled  to  stand 
with  the  water  level  about  breast  high,  or  at  a  convenient  height  for  accurate  observation.  The 
methods  of  measuring  water  over  this  weir  are  those  described  in  Lowell  Hydraulic  Experiments,  by 
James  B.  Francis. 

A  platform  R  surrounds  the  tailrace,  and  is  suspended  from  the  iron  beams  that  roof  it  in.  The 
wheels  to  be  tested  are  lifted  from  the  wagon  or  cars  by  a  traveling  windlass,  and  run  into  the  building 


1 62  HYDROELECTRIC  DEVELOPMENTS  AND  ENGINEERING. 

and  lowered  into  the  wheel  pit  D  Winding  stairs  S  lead  into  a  passageway  that  leads  in  turn  to  the 
platform  R.  In  the  well  hole  of  these  stairs  is  set  up  the  glass  tube  X,  which  measures  the  head  of 
water  upon  the  wheel.  It  is  connected  with  the  pit  D  by  means  of  pipe  running  through  a  cast-iron  pipe 
T,  built  into  the  masonry  dam  which  forms  the  downstream  end  of  the  wheel  pit  D.  The  power  is 
weighed  by  a  Prony  brake,  consisting  of  a  cast-iron  pulley  surrounded  by  a  wood-lined  jacket,  cooled 
and  lubricated  by  water  from  the  city  mains,  or,  if  necessary,  with  the  addition  of  a  small  stream  of 
soap-water.  The  pull  of  the  jacket  is  weighed  by  a  bent  lever  and  weights,  the  friction  being  regulated 
by  an  attendant  at  the  temper  screw,  so  that  the  weights  are  kept  balanced.  To  enable  the  observer 
at  the  brake  wheel,  the  one  at  the  head  gauge  and  the  one  at  the  measuring  weir,  to  take  simultaneous 
observations  at  intervals  of  one  minute,  an  electric  clock  is  set  up,  which  rings  three  bells  simultaneously 
at  intervals  of  one  minute,  or  of  half  a  minute  if  desired.  The  whole  structure  is  built  in  a  durable  and 
efficient  manner.  The  pits  and  tailrace  are  all  lined  with  brick  laid  in  cement.  The  stone  masonry 
was  intended,  by  careful  work  and  grouting,  to  be  water  tight  without  the  brick  lining,  and  the  brick 
lining  was  then  carefully  laid  up  with  joints  full  of  mortar,  as  an  extra  precaution.  As  a  consequence, 
the  front  of  the  wall  forming  the  downstream  side  of  the  pit  D  is  built  so  tight  that  an  exact  measure- 
ment of  the  leakage  of  the  wheel  gate  could  be  made  if  desired.  An  approximate  estimate  is  readily 
made  by  filling  the  pit  before  the  tailrace  is  allowed  to  fill  up  and  apportioning  the  total  measured 
leakage  of  the  wheelgate  and  that  of  the  flume. 

W  shows  a  waste  pipe.  Another  not  shown  serves  to  draw  the  water  out  of  and  through  the  floor 
of  the  pit  D.  To  close  or  open  these  waste  pipes  they  are  fitted  with  cases  of  small  water  wheels,  which 
thus  form  convenient  valves  for  the  purpose  indicated. 

The  pipe  W  leads  into  a  sewer  on  the  other  side  of  the  second  level  canal  and  thence  into  the  river. 
It  enables  the  tailrace  to  be  emptied  of  water  down  to  within  some  three  inches  of  the  bottom  plank- 
ing. After  the  wheel  to  be  tested  is  placed  in  the  flume,  and  the  dynamometer  placed  on  the 
shaft,  the  lever  is  adjusted,  care  being  taken  that  it  is  horizontal  and  tangent  to  the  circumference 
of  the  brake  at  point  of  application  of  the  pull.  It  is  balanced  by  placing  a  small  weight  first  on 
one  side  and  then  on  the  other  of  the  fulcrum,  and  at  equal  distances  from  it,  and  noting  the  time 
necessary  to  move  the  long  arm  a  certain  distance  above  and  below  the  center,  and  then  adjustment 
of  the  counterpoise  until  the  times  become  equal.  A  dashpot  is  always  used  with  the  lever  to  steady 
its  oscillations. 

An  indicator  is  attached  to  the  turbine  gate  or  to  the  mechanism  controlling  it,  so  that  the  position 
of  the  gate  is  always  known. 

The  hook  gauge  is  set  by  an  engineer's  level  so  that  point  of  hook  is  level  with  crest  of  weir  when 
scale  on  the  gauge  reads  zero.  The  length  of  the  weir  is  adjusted  to  the  proper  length  for  the  quantity 
of  water  to  be  measured.  The  floating  gauge,  by  which  head  on  wheel  is  measured,  is  adjusted  so 
that  the  zero  of  its  scale  is  at  the  level  of  tail  water. 

In  the  system  followed  there  are  three  observers,  each  taking  a  reading  of  his  gauge  every  minute 
and  keeping  a  separate  set  of  notes.  The  notes  from  which  the  theoretical  or  gross  power  of  the  water 
is  computed  are  kept  by  the  men  at  the  head  gauge  and  hook  gauge,  and  consist  of  a  simple  measure- 
ment of  the  head,  or  vertical  distance  from  surface  of  water  in  flume  over  the  wheel  to  surface  of  tail 
water,  the  length  of  the  measuring  weir,  the  number  of  its  end  contractions,  depth  of  water  flowing  over 
the  weir,  and  temperature  of  water. 

All  data  for  the  effective  power  of  the  wheel  are  taken  by  the  third  observer,  and  consist  of  the 
circumference  of  the  brake  at  point  of  application  of  the  weight,  ratio  of  the  lever  arms,  number  of 
pounds  on  the  lever,  revolutions  of  the  wheel  per  minute,  and  setting  of  the  wheelgate. 

Of  the  data,  all  excepting  setting  of  the  gate,  weight  on  lever,  revolutions,  head  and  depth  on  the 
weir,  are  generally  constant  throughout  one  wheel  test. 

The  variable  data  are  compared  with  each  other,  and  for  any  one  experiment  consecutive 
readings  are  selected  where  everything  goes  to  show  that  revolutions,  head,  and  depth  on  the  weir 
are  steady  and  consistent  with  each  other.  These  readings  in  each  notebook  are  then  averaged, 
and  these  averages  compose  the  variable  data  for  the  experiments,  a  full  set  for  each  change  of  weight 
on  the  lever. 


MECHANICAL  EQUIPMENT.  163 

The  quantity  of  water  passing  the  weir  is  computed  by  the  Francis  formula: 

Q  =  3.33  (L  —  .  i  nh)  h\,  in  which 
Q  =  quantity  in  cubic  feet  per  second. 
L  —  length  of  weir  in  feet. 

n  =  number  of  end  contractions. 

h  =  depth  on  the  weir. 

If  the  volume  of  water  renders  it  necessary,  Q  is  corrected  for  velocity  of  approach. 
Q  is  then  diminished  by  the  leak  of  flume  floor,  and  result  is  the  net  quantity  of  water  passing 
the  wheel. 

Theoretical  power  of  water  in  horsepower  is 

q  X  H  X  60  X  Wt 

HP.  (water)  =  -  , 

33,000 

in  which  q  =  cubic  feet  per  second  passing  the  wheel. 

H  =  head  on  wheel,  in  feet. 

Wt  =  weight  in  pounds  of  one  cubic  foot  of  water,  according  to  temperature. 

Effective  power  of  wheel  is 

W  X  R  X  I  X  c 

HP.  (wheel)  =  -  , 

33,000 

in  which  W  =  weight  in  pounds  on  lever-arm. 

R  -  -  revolutions  per  minute. 
I  =  ratio  of  lever-arms. 
c  =  circumference  of  brake. 

HP.  (wheel) 


Efficiency  of  wheel  = 


HP.  (water) 


On  account  of  fluctuations  in  height  of  the  canal  from  which  water  is  drawn  for  testing,  and  on 
account  of  varying  depth  of  water  over  the  weir,  the  head  on  wheel  is  not  constant  throughout  the 
test,  so  that  the  discharges  at  various  gates  and  speeds  cannot  be  directly  compared,  but  must  first  be 
reduced  to  a  uniform  head,  H',  by  the  rule 


Jir 

=  q\H' 


The  discharge  at  full  gate  and  at  the  speed  of  revolution  giving  the  maximum  efficiency,  is  taken 
as  the  unit  discharge,  and  the  discharge  (<?')  of  each  experiment  is  divided  by  it  so  that  in  the  final 
report,  the  column  of  "  proportional  discharge  "  shows  the  percentage  of  water  used  in  each  experiment. 

Deductions  from  Tests.  Having  given  above  a  description  of  how  a  test  is  made,  the  horsepower, 
speed  and  amount  of  water  discharged  by  the  same  wheel  under  any  head  is  deduced.  This  is  done 
in  the  first  place,  to  enable  any  one  who  so  desires  to  determine  for  himself  whether  a  wheel  that  has 
been  tested  and  the  test  made  known  has  been  correctly  tabled  as  to  its  horsepower,  speed  and  amount 
of  water  discharged,  or,  in  other  words,  whether  such  table  has  been  actually  deduced  from  such  test; 
in  the  second  place,  to  show  that  a  wheel  that  has  not  been  tested  cannot  be  correctly  or  reliably  tabled 
as  to  its  horsepower,  speed  and  discharge,  as  the  data  required  for  these  deductions  can  only  be  obtained 
by  means  of  a  test.  To  illustrate,  the  theoretical  discharge  of  a  wheel  under  a  given  head  can  be 
ascertained  by  measuring  the  cross  section  or  area  of  its  discharging  openings  and  multiplying  same  by 
the  theoretical  velocity  of  the  water  under  the  given  head,  but  the  actual  discharge  can  only  be  ascer- 


1  64  HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 

tained  by  measurement,  over  a  weir,  of  the  amount  of  water  actually  discharged  by  the  wheel  when  in 
operation.  The  ratio  of  the  actual  discharge  to  the  theoretical  discharge  is  called  the  coefficient  of 
discharge. 

The  discharge  being  known,  the  theoretical  power  of  the  water  can  be  ascertained  by  computa- 
tion by  formula  given  above,  but  the  actual  power  of  the  wheel  can  only  be  ascertained  by  measurement 
with  a  dynamometer  or  other  appliance.  The  ratio  of  actual  power  developed  to  the  theoretical  power 
is  the  efficiency  of  the  wheel. 

The  speed  of  a  wheel  of  given  diameter  under  a  given  head  is  due  to  the  velocity  of  water  under 
that  head,  and  the  ratio  of  the  actual  to  the  theoretical  speed  is  the  coefficient  of  speed  or  relative  velocity. 
Without  these  three  coefficients  it  is  impossible  to  table  a  wheel  as  to  power,  speed  and  discharge. 

Any  tables  of  power  without  an  accompanying  test  to  show  how  same  have  been  deduced  should  be 
condemned,  and  any  tables  of  power  accompanied  by  test  should  be  carefully  examined  to  ascertain 
whether  same  have  been  correctly  deduced.  Such  a  course  will  save  the  purchaser  the  expenditure  of 
money  and  avoid  future  trouble. 

The  potential  energy  of  a  mass  of  water  is  its  weight  multiplied  by  the  distance  it  has  to  fall.  This 
product  of  the  weight  into  the  head  gives  the  work  the  water  performs  in  foot-pounds.  Thus  1000 
cubic  feet  of  water  weigh  62,333  pounds,  and  falling  10  feet  develops  623,330  foot-pounds  of  energy, 
and  dividing  by  33,000  gives  the  horsepower.  The  horsepower  a  turbine  will  develop  from  this  quan- 
tity of  water  depends  upon  the  efficiency  of  the  wheel  as  ascertained  by  test. 

The  quantity  of  water  (say  in  cubic  feet  per  second)  which  will  discharge  (theoretically)  through 
an  aperture  under  a  given  head  is  ascertained  by  multiplying  the  area  of  the  aperture  in  square  feet  by 
the  velocity  of  the  water  in  feet  per  second  due  that  head,  and  the  area  of  the  aperture  remaining  the 
same,  the  quantity  discharged  under  different  heads  varies  as  the  velocity.  So  the  quantity  under 
any  head  being  known,  the  quantity  under  any  other  head  may  be  ascertained  by  the  proportion 

OV 
Q  :  Q'  :  :  V  :  V,  or  Q'  =  -  •     In  the  same  way  the  quantity  of  water  discharging  through  a  tur- 

bine under  different  heads  varies  as  the  velocity. 

Having  by  test  measured  the  quantity  of  water  discharged  by  the  turbine,  and  also  the  head,  the 
discharge  under  any  other  head  is  obtained  by  the  above  formula  and  entered  in  the  table. 

Having  thus  ascertained  the  discharge  in  cubic  feet  per  minute  for  any  head,  the  horsepower  is 
obtained  by  multiplying  the  quantity  by  625  (the  weight  of  a  cubic  foot  of  water),  this  product  by  the 
head  in  feet,  and  dividing  the  result  by  33,000  and  multiplying  by  the  per  cent  of  useful  effect,  or  by  the 

formula  (2)  HP.  =  -  -  -  X  %  efficiency.     The  per  cent  of  efficiency  is  obtained  by  divid- 

33,000 

ing  the  actual  by  the  theoretical  horsepower. 

It  will  be  seen  in  formula  (2)  that  the  horsepower  varies  as  the  quantity  and  the  head,  the  other 
elements  of  the  formula  remaining  constant.  Therefore  the  horsepower  varies  as  the  velocity  and  the 
head,  and  the  horsepower  under  any  other  head  can  be  ascertained  by  the  proportion 

HP  X  V  y.  H' 
HP  :  HP'  ::V  XH  :V  XH',or  the  formula  (3)  HP'  = 


V  X  H 

The  speed  of  a  wheel  is  due  to  the  velocity  of  the  water  which  drives  it.  For  example,  the  velocity 
of  water  due  to  fourteen  feet  head  is  thirty  feet  per  second,  or  1800  feet  per  minute. 

A  wheel  three  feet  in  circumference,  therefore,  would  make  600  turns  per  minute.  This  would  be 
the  theoretical  speed  of  the  wheel  without  regard  to  contracted  discharge.  The  actual  speed  is  taken 
during  the  test  by  an  indicator,  and  the  relative  velocity  -ascertained.  It  follows,  therefore,  that  the 
revolutions  vary  as  the  velocity;  the  revolutions  under  any  other  head  may  be  ascertained  by  the  pro- 
portion, R  :  R'  :  :  V  :  V,  or  the  formula  (4) 


MECHANICAL  EQUIPMENT.  165 


BIBLIOGRAPHY. 

MODERN  TURBINE  PRACTICE.     John  Wolf  Thurso.     1905.    Van  Nostrand.    New  York. 

HYDRAULIC  MOTORS.     Irving  P.  Church.     1905.     Wiley  &  Sons.     New  York. 

HYDRAULIC  POWER  AND  ENGINEERING.     G.  Croiden  Marks.     1900.    Van  Nostrand.     New  York. 

WATER  POWER  ENGINEERING.     Daniel  W.  Mead.     1908.     McGraw  Company.     New  York. 

DIE  THEORIE  DER  WASSERTURBINENEN.    Rudolf  Escher.     Julius  Springer.     Berlin. 

DIE  TURBINEN  FUR  WASSERKRAFTBETRiEB.     A.  Pfarr.     1906.     Julius  Springer.     Berlin. 

TURBINEN  UNO  TuRBiNENANLAGEN.     Viktor  Gelpke.     1907.     Julius  Springer.     Berlin. 

NEUERE  TURBINENANLAGEN.     Wilhelm  Wagenbach.     1905.     Julius  Springer.     Berlin. 

DIE  AUTOMATISCHE  REGULiERUNG  DER  TURBINEN.     Walther  Bauerfeld.     1906.     Julius  Springer. 

Berlin. 

WASSERKRAFTMASCHINEN.     L.  Quantz.     1906.     Julius  Springer.     Berlin. 
THE  NEED  OF  TURBINE  STANDARDS  OF   MEASUREMENT.    M.  A.  Reployle.    Engineering  News, 

Oct.  23,  1902. 
MODERN  TURBINE  PRACTICE  AND  THE  DEVELOPMENT  OF  WATER  WHEELS.     John  Wolf  Thurso. 

Engineering  News,  Dec.  4,  1902. 
TURBINES  AND  THE  EFFECTIVE  UTILIZATION  OF  WATERPOWER.    Alex  Rea.    Mechanical  Engineer, 

March  22,  1902. 

EFFECT  OF  DRAFT  TUBES.     John  Wolf  Thurso.    Engineering  News,  vol.  i,  p.  29.     1903. 
TANGENTIAL  WATER  WHEEL  BUCKETS.     The  Engineer,  May  i,  1904. 
NOTES  ON  THE  PURCHASE  AND  USE  OF  HYDRAULIC  TURBINES.    W.  Kennely,  Jr.    Canadian  Society 

of  Civil  Engineers,  Bulletin  No.  2,  December,  1907. 

HYDRAULIC  TURBINE  PRACTICE.    Frank  Koester.    Practical  Engineer.    April,  May,  1909. 
THE  THEORY  OF  IMPULSE  WHEELS.    Kingsford.    Engineering  News,  July  21,  1898. 
REPORT  OF  A  TURBINE  TEST.    Webber.    Engineering  News,  April  20,  1903. 
THE  GOVERNING  OF  IMPULSE  WHEELS.    I.  P.  Church.    Engineering  Record,  Feb.  25,  1905. 
NOTES  ON  GOVERNING  HYDRAULIC  TURBINES.    R.  S.  Ball.    Engineering,  Aug.  23,  1907. 
A  NEW  METHOD  OF  TURBINE  CONTROL.    Lamar  Lyndon.     A.  I.E.  E.,  May,  1906. 
SOME  STEPPING  STONES  IN  THE  DEVELOPMENT  OF  A  MODERN  WATER  WHEEL  GOVERNOR.    Mark  A. 

Replogle.     A.  S.  M.  E.,  May,  1906. 
ELEMENTS  OF  DESIGN  FAVORABLE  TO  SPEED  REGULATION  IN  PLANTS  DRIVEN  BY  WATER  POWER. 

Allen  V.  Garratt.     A.  I.  E.  E.,  June  27,  1899. 
SPEED  REGULATION  OF  HIGH  HEAD  WATER  WHEELS.    H.  E.  Warren.     Technology  Quarterly,  June, 

1907. 

A  NEW  METHOD  OF  GOVERNING  WATER  WHEELS.    Sibley  Journal  of  Engineering,  March,  1896. 
GOVERNING  OF  WATER  POWER  UNDER  VARIABLE  LOADS.     A.  S.  C.  E.,  June,  1897. 
WATER  WHEEL  REGULATION.     Samuel  N.  Knight.    Journal  of  Electricity,  November,  1897. 
MODERN  PRACTICE  OF  WATER  WHEEL  OPERATION.    Electrical  World,  May  5,  1900. 
COMMERCIAL  REQUIREMENTS  OF  WATERPOWER  GOVERNING.    Elmer  F.  Cassel.    Engineering  Maga- 
zine, September,   1900. 

A  WATER  WHEEL  GOVERNOR  OF  NOVEL  CONSTRUCTION.    Engineering  News,  Nov.  13,  1902. 
SPEED  REGULATION  IN  WATERPOWER  PLANTS.     J.  W.  Thurso.     Engineering  News,  1903,  vol.  i, 

p.  27. 

THE  GOVERNING  OF  IMPULSE  WHEELS.     John  Goodman.    Engineering,  Nov.  4,  1904. 
THE  REGULATION  OF  HIGH  PRESSURE  WATER  WHEELS  FOR  POWER  TRANSMISSION  PLANTS.    George 

J.  Henry,  Jr.     A.  S.  M.  E.,  May,  1906. 
TURBINE  DESIGN  AS  MODIFIED  FOR  CLOSE  REGULATION.     George  O.  Buvinger.     A.  S.  M.  E.,  May, 

1906. 

SURGE  TANKS  FOR  WATERPOWER  PLANTS.    R.D.Johnson.     A.  S.  M.  E.,  1908. 
THE  GLOCKER-WHITE  TURBINE  GOVERNOR.    W.  M.  White  and  L.  F.  Moody.    Power,  4,  1908. 


166  HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 

THE  EFFICIENCY  OF  WATER  WHEELS.     F.  M.  F.  Cazin.    Electrical  World,  Jan.  9,  1897. 
IMPULSE  WATER  WHEEL  EXPERIMENTS.     E.  A.  Hitchcock.    Electrical  World,  June  5,  1897. 
SYSTEMATIC  TESTING  OF  TURBINE  WATER  WHEELS  IN  THE  UNITED  STATES.    R.  H.  Thurston.    Am. 

Soc  M.  E,  1897,  p.  359. 

TANGENTIAL  WATER  WHEEL  EFFICIENCIES.    G.  J.  Henry,  Jr.    Am.  Inst.  E.  E.,  Sept.  25,  1903. 
EXPERIMENTS  AND  FORMULA  FOR  THE  EFFICIENCY  OF  TANGENTIAL  WATER  WHEELS.     B.  F.  Groat 

Engineering  News,  1904,  vol    2,  p.  430 
EFFICIENCY  TESTS  OF  TURBINE  WATER  WHEELS.     Wm.  O.  Webber.     Am.  Soc.  M.  E.,  May,  1906. 


A.E.&M. 

UNIV.  OF  C> 


CHAPTER   VII. 
ELECTRICAL   EQUIPMENT. 

GENERATORS. 

Classification.  In  modern  high-tension  transmission  systems,  alternating  current 
generators  are  practically  exclusively  used.  They  are  wound  either  for  single, 
two  or  three  phase,  and  connected  either  in  star  or  delta.  The  choice  of  any  of 
the  three  systems  depends  on  the  character  of  the  transmission  system.  The 
generators  are  classified  as  inductor,  revolving  armature  and  revolving  field 
type. 

Inductor  Generator.  This  type  of  generator  derives  its  name  from  the  projecting 
ends  of  the  rotating  element  which  are  termed  inductors.  The  chief  advantage  of 
this  generator  is  that  there  is  no  rotating  winding,  as  both  field  and  armature  wires 
are  stationary.  The  rotating  element  is  nothing  but  a  mass  of  iron,  consisting  of  a 
cast  spider  made  in  two  or  more  parts,  depending  on  the  size. 

The  rim  of  the  spider  is  provided  with  lugs,  to  which  the  laminated  pole  pieces 
are  fastened.  Due  to  the  simple  construction  of  the  revolving  element,  high 
peripheral  speed  may  be  attained  without  setting  up  excessive  stresses. 

As  seen  in  Fig.  i,  the  field  coil  is  stationary  and  clamped  in  the  middle  of  the 
machine.  Its  winding  consists  of  copper  wire  or  strips,  properly  insulated  and 
well  ventilated.  As  it  is  not  necessary  to  surround  each  individual  pole  piece  on  all 
four  sides  with  copper  winding,  the  amount  of  copper  used  in  winding  these  field 
coils  is  less  than  that  in  revolving  field  generators. 

The  armature  winding  usually  employed  is  what  is  called  the  "concentrated 
winding,"  that  is,  there  is  only  one  slot  per  phase  per  pole.  The  percentage  of  space 
taken  up  by  the  insulation  in  this  style  of  winding  is  less  than  that  in  the  "distrib- 
uted winding,"  consequently  more  space  is  left  for  copper  conductors,  a  factor 
which  is  of  special  importance  in  high-voltage  machines.  They  are  wound  for  2300 
or  6600  volts,  and  usually  are  of  the  two  or  three  phase  type. 

The  pressure  wave  of  an  induction  alternator  can  be  made  to  closely  approach  a 
pure  sine  curve,  a  factor  of  great  importance  in  long-distance  lines,  and  also  in 
connection  with  arc  lamps. 

The  efficiency  for  both  full  and  partial  load  is  high,  which  is  partly  due  to  the 
fact  that  the  magnetization  of  the  iron  is  never  reversed,  but  merely  increases  from 
zero  to  maximum  value  and  then  decreasing  to  zero;  if  the  iron  is  worked  at  ordinary 
densities,  the  iron  losses  are  small.  As  a  rule,  the  regulation  of  inductor  alternators 
is  not  as  close  as  that  of  the  revolving  field  type. 

167 


168  HYDROELECTRIC    DEVELOPMENTS    AND    ENGINEERING. 


FIG.  i. — Sections  of  an  Induction  Generator,  General  Electric  Company. 


FIG.  2. — 5000-HP.,  azo-volt,  Umbrella  type,  2-phase  Alternator  with  Internal 
Stationary  Armature,  Niagara  Falls  Power  Company,  Plant  No.  2. 


ELECTRICAL  EQUIPMENT 


169 


Revolving  Armature  Generator.  The  armature  in  this  type  of  alternator  consists 
of  laminated  steel  rings,  mounted  on  the  cast-iron  rim  of  a  wheel.  The  armature 
ring  is  built  up  of  thin  sheet  steel  punched  in  such  a  way,  that  when  assembled,  the 
completed  armature  core  is  pierced  with  slots  for  the  reception  of  the  winding; 
ventilating  spaces  are  provided  at  intervals,  as  the  armature  is  assembled. 


FIG.  3. — 225-K.W.,  4oo-volt,  5o-cycle,  3-phase,  Flywheel  Alternator, 
with  Internal  Stationary  Armature,  and  Exciter. 

According  to  the  amount  of  current  to  be  carried,  the  winding  consists  of  wire, 
straps  or  bars.  For  high-voltage  alternators  of  small  current  capacity,  wire  wind- 
ing, in  machine  wound  coils,  is  used.  For  low  voltage  and  large  current  capacity 
strap  wound  windings  are  employed.  Copper  bars  are  used  where  the  current  in 
the  armature  is  very  high. 

The  fields  of  large  alternators  are  made  in  two  or  more  pieces,  the  division  being 
vertical  or  horizontal,  so  that  the  frame  may  be  removed  and  the  armature  winding 
is  easily  accessible.  The  field  poles  are  made  up  of  thin  annealed  steel  plates  and 
are  bolted  into  the  field  yoke. 


I/O  HYDROELECTRIC    DEVELOPMENTS    AND   ENGINEERING. 

In  small  alternators,  the  field  coils  are  made  of  wire  instead  of  straps,  used  in 
large  alternators.  When  strap  winding  is  used,  the  strap  is  wound  on  edge.  This 
type  of  alternator  is  not  used  to  any  extent  for  high-tension  transmission;  its  field  is 
confined  to  isolated  or  similar  power  plants. 

Revolving  Field  Alternator.  As  classified  by  the  name,  in  this  type  of  alternator, 
the  field  revolves  while  the  armature  is  stationary.  This  method  of  construction 
facilitates  the  insulation  of  the  armature  winding  and  requires  that  field  current 
instead  of  the  armature  current  shall  pass  through  the  collector  rings  and  brushes. 
Due  to  this,  alternators  of  this  type  are  specially  adapted  for  high  voltages  for  large 
current  output. 

The  revolving  element  or  field  consists  of  a  wheel,  upon  the  rim  of  which  are 
mounted  laminated  plates,  bolted  together;  at  intervals  are  air  spaces  for  ventilation. 
As  these  pole  pieces  are  built  on  the  circumference  of  the  rim,  the  revolving  element 
frequently  serves  the  purpose  of  a  flywheel,  particularly  in  connection  with  low-head 
turbine  plants  where  the  speed  is  low. 

The  field  coils,  according  to  the  size  of  generator,  are  either  of  wire  or  copper 
strap  wound  on  edge.  When  placed  in  position  on  the  frame,  they  are  securely 
held  by  wedges. 

The  armature  winding  is  stationary  and  usually  external  to  the  field  (armature 
internal  to  the  field  and  stationary  is  seen  in  Fig.  2)  and  carried  in  the  frame  of 
the  machine.  The  winding  is  similar  to  that  of  the  revolving  armature  type.  The 
stationary  parts  for  small  machines  are  made  in  one  piece,  and  so  arranged  that  the 
whole  frame  can  be  shifted  for  inspection.  In  large  machines  the  frame  is  split  up 
into  sections  for  inspection  and  repair  purposes. 

Regulation.  According  to  the  standardization  committee  of  the  American  Insti- 
tute of  Electrical  Engineers,  the  regulation  of  an  apparatus  intended  for  the  genera- 
tion of  a  potential,  current,  speed,  etc.,  varying  in  a  definite  manner  between 
full  and  no  load,  is  to  be  measured  by  the  maximum  variation  of  potential,  current, 
speed  and  so  forth,  from  the  satisfied  condition  under  such  constant  conditions  of 
operation  as  give  the  required  full  load  values.  The  regulation  of  an  alternator  is 
the  percentage  rise  in  voltage  obtained  by  throwing  off  the  entire  non-inductive  full 
load.  The  speed  and  excitation  of  course  are  constant.  Good  machines  have  a 
regulation  of  6  per  cent  on  non-inductive  loads  and  8  per  cent  on  inductive  loads 
with  a  power  factor  of  0.85. 

Where  synchronous  machines  are  connected  to  the  transmission  line,  close  regu- 
lation of  the  generators  is  very  essential.  As  these  machines  run  in  synchronism 
with  the  generator,  any  sudden  variation  in  generator  voltage  is  transmitted  to  the 
synchronous  apparatus,  which  cannot  respond  owing  to  the  inertia  effect  of  the 
rotating  element.  If  the  changes  are  very  sudden,  the  synchronous  machines  will  fall 
out  of  step  and  eventually  stop.  For  slight  changes,  the  speed  of  the  synchronous 
machine  will  try  to  keep  step  with  the  generator.  This  action  is  known  as 
"  hunting." 

Where  the  alternator  is  subject  to  much  fluctuation  in  voltage,  an  automatic 
regulator  facilitates  the  regulation  of  the  machine,  that  is,  it  automatically  controls 


ELECTRICAL  EQUIPMENT. 


171 


the  exciter  current  to  give  nearly  constant  voltage  at  the  generator  terminals.  It  has 
this  advantage:  it  is  independent  of  the  inherent  regulation  of  the  machine  itself  and 
gives  superior  results.  As  an  alternator  with  high  regulation  is  expensive,  it  is 
often  cheaper  to  install  an  automatic  regulator  on  a  machine  with  inferior  regulation. 
The  Tirrell  Regulator  is  used  on  constant-potential  circuits  and  the  Thury  on  con- 
stant-current. 


FIG.  4. — Eleven  i2oo-HP.,  Sooo-volt,  5o-cycle,  66-R.P.M.,  3-phase,  Brown,  Boveri 
Alternators.     In  Front  two  4OO-HP.  Exciters,  Beznau  Plant,  Switzerland. 

Efficiency.  The  efficiency  of  a  generator  is  the  ratio  of  the  power  output  to  the 
power  input  and  is  expressed  in  per  cent.  Some  of  the  best  machines  have  an  efficiency 
as  high  as  98  per  cent.  However,  average  efficiencies  are  in  the  neighborhood  of 
96  per  cent.  As  the  efficiency  of  a  generator  depends  exclusively  on  the  design 
and  workmanship,  it  is  the  best  policy  for  the  manufacturer  to  produce  a  machine  of 
highest  efficiency,  and  the  power  plant  designer  must  not  hesitate  to  use  same.  The 
efficiencies  must  be  high,  not  only  on  a  full  load,  but  correspondingly  high  on  frac- 
tional loads. 

It  is  the  practice,  particularly  in  plants  supplying  power  for  railroad  purposes, 
to  operate  the  generators  at  50  per  cent  overload.  The  highest  efficiency  is  usually 
attained  at  25  per  cent  overload.  This  indicates  that  the  generator  is  designed  for 
greater  capacity  than  actually  rated  by  the  manufacturer.  European  manufacturers 


HYDROELECTRIC    DEVELOPMENTS    AND   ENGINEERING. 


HO  0 


aaaa 


MOD. 


$«0 


10  v 


2190 


FIG.  5. — Characteristic  Curves  of  275O-K.V.A.  Generator.     9000-10,500  volts, 

150  amperes,  42  cycles. 

E0  =  No-load  characteristic.  4  =  Armature  copper  loss  at  cos  <£  =  0.75. 

Jc  =  Short  circuit  characteristic.  5  =  Exciter  loss  at  cos  <f>  =  0.75. 

n  =  Efficiency.  6  =  Armature  copper  loss  at  cos  «£  =  i.oo. 

2  =  Iron  loss.  7  =  Exciter  loss  at  cos  0  =  i.oo. 

3  =  Friction  and  Windage  loss. 


FIG.  6. — 2750-K.V.A.,  9ooo-io,5oo-volts,  42-cycle,  3I5-R.P.M.,  3-phase  Alternator  (Oerlikon) 
connected  to  an  Impulse  Wheel,  Caffaro  Plant,  Italy. 


ELECTRICAL  EQUIPMENT.  173 

rate  their  machines  according  to  the  capacity  at  highest  efficiencies,  and  the  over- 
load capacity  is  usually  25  per  cent.  When  these  concerns  sell  their  machines  to 
foreign  countries,  where  50  per  cent  overload  capacity  is  required,  they  follow  the 
practice  in  America,  that  is,  they  underrate  the  generator.  Fig.  5  shows  the  charac- 
tistic  curves  of  a  2750-]$.. V.A.  generator,  which  is  given  in  Fig.  6.  When  generators 
continuously  run  for  24  hours,  the  temperature  rise  of  any  part  of  the  machine  must 
not  exceed  from  40  to  45°  C.  for  normal  load  with  a  power  factor  of  0.90  to  i.oo. 
With  the  same  power  factor  the  rise  in  temperature  on  25  per  cent  overload  must  not 
exceed  50°  C.,  and  with  50  per  cent  overload  for  one  hour  the  rise  must  not  exceed 
60°  C.  above  that  of  the  surrounding  temperature. 

Frequencies.  The  most  common  frequencies  used  are  25  and  60,  and  depend 
chiefly  on  the  character  of  service;  25  is  used  for  power  purposes  and  60  for  lighting. 
However,  there  are  exceptions  where  the  reverse  is  true.  The  lower  frequency  is 
chosen  because  the  iron  losses  in  the  generators  are  less  and  consequently  the 
machine  is  cheaper.  The  higher  frequency  is  used  for  lighting,  as  it  does  away  with 
fluctuation.  Synchronous  machines,  such  as  rotary  converters,  give  much  trouble 
on  6o-cycle  lines,  and  in  their  stead  motor-generator  sets  are  substituted,  as  will  be 
seen  in  chapter  on  Substations. 

In  the  last  few  years  15  cycles  have  been  used  for  railroading,  particularly  in 
connection  with  single  phase,  and  it  is  still  being  discussed  in  the  technical  press 
whether  or  not  it  should  be  adopted  as  a  standard.1  The  principal  arguments  in 
favor  of  15  cycles  are  given  as  : 

1.  An  increase  of  from  30  to  40  per  cent  in  the  output  of  a  motor  of  a  given  size, 
and  a  consequent  reduction  in  the  total  number  of  motors  required  to  operate  a  rail- 
way, and  in  the  cost  of  equipment. 

2.  Better  performance  of  the  i5~cycle  motors,  including  higher  efficiency,  higher 
power  factor,  and  better  commutation. 

3.  Less  dead  weight  to  be  carried  on  cars  and  locomotives. 

4.  Lower  line  losses. 

In  other  countries  the  choice  of  frequencies  varies  greatly;  for  instance,  one  will 
find  frequencies  of  15,  25,  32.5,  42,  60,  etc. 

Voltage.  For  low-tension  distribution,  voltages  of  no,  220,  and  440  may  be  con- 
sidered as  standard.  For  higher  generator  voltages,  noo,  2200,  3300,  6600,  n,ooo, 
and  12,000  are  most  frequently  used  in  American  practice.  The  choice  of  voltage 
depends  chiefly  on  the  system  of  distribution,  particularly  for  long-distance  trans- 
mission. When  the  bulk  of  the  power  is  used  in  the  vicinity,  the  voltage  of  the  gen- 
erator must  be  chosen  to  suit  the  most  economical  distribution,  that  is,  to  reduce  the 
use  of  transformers  to  a  minimum.  When  the  power  is  transmitted  over  a  long 
distance,  one  of  the  above  generator  voltages  is  used  and  stepped  up  to  a  suitable 
transmission  voltage. 

Exciters.  The  exciters  are  driven  either  by  a  separate  turbine  or  from  the  shaft 
of  the  main  unit.  In  the  latter  case  each  generator  has  its  own  exciter  and  is 

1  Twenty-five  versus  Fifteen  Cycles  for  Heavy  Railways,  by  N.  W.  Storer.  Am.  Inst.  E.  E.,  July, 
1907. 


174 


HYDROELECTRIC    DEVELOPMENTS    AND   ENGINEERING. 


FIG.  7. — Interior  of  Submerged  Power  Plant  of  the  Patapsco  Electric  and  Manufacturing 
Company.  3OO-K.W.,  3-phase,  6o-cycle,  n,ooo-volt  Allis-Chalmers  Alternators,  running 
240  R.P.M. 


FIG.  8. — Interior  of  Sill  Plant,  Insbruck,  Tyrol.     Each  Unit  consists  of  two  Impulse  Wheels, 
Zodel  Coupling,  and  a  2ooo-K.W.,  io,ooo-volt  Generator  with  Overhanging  Exciter. 


ELECTRICAL   EQUIPMENT.  175 

seldom  belt-driven,  but  is  mounted  on  the  overhanging  shaft  of  the  generator;  it 
is  therefore  dependent  on  the  operation  of  the  main  unit,  the  disadvantage  being, 
in  case  the  speed  of  the  main  unit  should  drop  the  excitation  diminishes,  thus  neces- 
sitating the  installation  of  an  automatic  regulator.  With  a  turbine-driven  exciter 
the  excitation  of  the  generator  is  independent  of  its  speed. 

The  exciter  has  the  same  type  of  turbine  as  the  main  unit.  Lighting  of  the 
station  is  frequently  supplied  by  the  exciter  units.  The  voltage  of  the  exciters 
depends  much  on  the  voltage  used  for  lighting  purposes,  also  for  operating  plant 
auxiliaries. 

In  connection  with  the  exciters,  storage  batteries  are  installed  which  float  on  the 
exciter  busses  to  take  care  of  fluctuations  and  peak  loads.  This  is  particularly  true 
where  the  exciters  are  mounted  on  the  main  generator  shaft.  Current  may  be  drawn 
from  the  storage  batteries  for  operating  the  high-tension  oil  switches.  When  the 
turbine-driven  exciter  is  employed  there  must  be  more  than  one,  to  take  care  of 
emergency  cases.  In  small  or  average-size  plants  the  exciter  is  of  sufficient  capacity 
to  excite  all  of  the  generators  at  once,  while  the  second  unit  is  kept  in  reserve.  In 
plants  above  say  50,000  K.W.  capacity  it  is  good  policy  to  install  several  exciter 
units  instead  of  two.  These  are  so  connected  that  they  feed  one  common  bus  from 
which  the  main  units  are  excited.  The  size  of  the  exciters  is  from  one-half  to  one 
per  cent  of  the  output  of  the  plant,  and  as  reserve  must  be  provided,  the  combined 
capacity  is  about  two  per  cent  of  that  of  the  plant.  The  voltage  usually  employed 
for  American  or  British  practice  is  either  125  or  250  volts. 

Generator  Leads.  The  generator  leads  to  the  switchboards  must  run  as 
inconspicuously  as  possible.  They  are  laid  in  the  floor  either  in  tile,  lori- 
cated,  iron,  or  other  approved  ducts.  A  more  convenient  way,  particularly  in 
large-sized  plants,  is  to  run  the  leads  in  trenches  or  tunnels,  on  insulators;  and 
must  be  so  arranged  that  the  cables  may  be  easily  inspected;  and  free  from  any 
possible  chance  of  short  circuit.  The  size  of  the  leads  is  always  specified  by  the 
manufacturer. 

High  Voltage  Generators.  The  advantages  of  high  voltage  generator  plants  lie 
in  lower  first  cost,  low  operating  expenses,  simplicity  in  station  wiring  and  better 
line  regulation.  With  the  employment  of  high  voltage  generators,  transformers  and 
their  attendant  troubles  are  eliminated.  A  3o,ooo-volt  generator  is,  of  course,  more 
expensive  than  a  6ooo-volt  or  other  low  voltage  generator.  However,  taking  into  con- 
sideration the  step-up  transformers  necessary  with  low  voltage  generators,  the  cost 
for  high  voltage  generators  is  lower;  further,  with  the  latter  equipment,  the  power 
house  is  smaller  and  therefore  less  expensive. 

The  simplicity  in  the  station  wiring  is  at  once  evident;  there  are  no  low  tension 
bus  systems,  with  switches,  transformers  and  measuring  instruments,  therefore  no 
special  low  tension  compartments  are  necessary.  However,  better  and  more  expen- 
sive instrument  transformers  are  required.  The  operating  performance  of  the 
station  is  simplified,  there  being  no  step-up  transformers  to  look  after  when  generators 
are  put  into  service;  when  generators  are  to  be  run  in  parallel  and  thrown  on  the 
line,  all  that  is  necessary  is  to  bring  the  incoming  machines  to  synchronism  and 


176  HYDROELECTRIC    DEVELOPMENTS    AND    ENGINEERING. 

throw  them  onto  the  bus.  The  absence  of  transformers  relieves  the  system  of  surges, 
attendant  when  throwing  unloaded  transformers  onto  the  busses. 

That  there  is  sufficient  reliability  in  operating  high  voltage  generators  is  proven 
by  the  number  of  such  generator  plants  on  the  continent  of  Europe;  for  instance, 
the  2o,ooo-volt,  3-phase,  i5-cycle  generator  plant  at  Ponte  de  Desco,  operating 
the  Valtellina  Railroad,  Italy.  Further,  a  15,000- volt,  42-cycle,  2-phase  gene- 
rator plant  at  Jaruga,  Dalmatia,  which  has  been  in  operation  since  1903,  feeding  a 
six  mile  aerial  transmission  system. 

Owing  to  the  successful  operation  of  this  latter  plant,  in  1906,  another  plant 
(Manojlovac,  Dalmatia)  was  put  into  operation  by  the  same  company  for  the  same 
purpose.  This  plant  possesses  four  6ooo-HP.  Francis  turbines,  directly  connected 
to  42-cycle,  3-phase  generators,  making  420  R.P.M.  The  30,000  generator- voltage 
is  transmitted  over  a  twenty-one  mile  aerial  line. 


SWITCHING    ROOMS. 

General  Arrangement.  The  switching  rooms  are  located  either  in  the  power 
house  itself  or  in  a  separate  building.  The  latter  is  exclusively  done  in  connection 
with  large  power  plants;  in  such  cases  only  the  controlling  apparatus  are  located  in 
the  power  plant,  while  the  entire  switchgear  for  the  outgoing  feeders  is  in  a  separate 
building,  some  distance  away.  Examples  of  this  arrangement  are  that  of  the 
Ontario  Power  Company,  and  the  Canadian-Niagara  Power  Company.  However, 
in  smaller  and  average  sized  plants  the  whole  switchgear  is  embodied  in  the  gene- 
rating plant,  and  if  transformers  are  necessary  they  are  located  in  the  same  building 
or  in  an  annex.  The  majority  of  hydroelectric  power  plants  are  of  the  latter 
type. 

It  is  decidedly  bad  practice  to  have  the  whole  switchgear  located  in  one  single 
room.  It  must  be  separated  regarding  high  and  low  tension,  transformers,  etc., 
either  on  separate  floors  or  separated  by  partition  walls.  An  example  of  this  kind 
of  arrangement  is  given  in  Fig.  i,  representing  the  relation  of  the  various  divisions 
of  the  Obermatt,  Lucerne,  power  plant.  It  is  considered  one. of  the  best  Swiss 
plants. 

It  will  be  observed  that  the  switching  apparatus  is  located  on  three  floors.  The 
two  lower  are  each  separated  by  two  longitudinal  division  walls;  the  upper  is  located 
in  the  tower-like  structure  from  whence  the  long  distance  lines  leave  the  building. 
The  6000  generator- voltage  is  stepped  up  to  27,000  volts  through  transformers 
located  in  an  annex,  longitudinal  to  the  switching  room. 

Good  examples  of  American  switching  room  practice  are  given  in  Figs.  3  and  4. 
Studying  the  cuts  of  the  Shawinigan  Falls  Power  Plant,1  it  will  be  observed  that 
the  2200  generator- voltage  is  led  to  a  separate  switchboard,  controlling  the  25,000 
and  5o,ooo-volt  transmission  groups.  Beneath  the  switchboard  gallery  in  the  gen- 
erating room  are  the  oil  switches,  while  the  two  groups  of  lightning  arresters  are 

1  Electric  Power  from  Shawinigan  Falls,  Canada,  by  W.  C.  Johnson,  Gassier 's  Magazine,  June,  1904. 


ELECTRICAL  EQUIPMENT. 


177 


kept  in  separate  compartments.  Another  very  interesting  arrangement  of  switching 
rooms  is  that  of  the  Puyallup  River  plant  of  the  Puget  Sound  Power  Company, 
near  Tacoma,  Washington.  Owing  to  the  fact  that  the  plant  is  located  on  the 


FIG.  i. — Cross  Section  of  Obermatt  Transformer  and  Switch  Rooms. 

MA  =  Circuit  Breakers. 
MO  =  Overload  Switches. 

T  =  Transformers. 

/  ==  Induction  Coils. 

B  =  Horn  Gaps. 
WW  =  Water  Rheostats. 
WS  =  Water  Flow  Grounder's. 


hillside,  the  whole  switching  gear  is  located  in  two  adjoining  buildings  as  seen  in 

Fig-  5-1 

The  transformer  rooms  are  at  the  same  level  as  the  generator  room,  but  isolated 

from  the  latter  by  rolling  steel  doors.  On  floor  No.  2  are  the  low  tension  discon- 
necting switches,  the  generator  and  transformer  cables  going  to  the  sets  of  discon- 
necting switches  on  either  side  of  the  middle  partition;  the  disconnecting  switches  are 

1  Electrical  World  and  Engineer,  October  8,  1904. 


178 


HYDROELECTRIC    DEVELOPMENTS    AND    ENGINEERING. 


.  _  '     /       \      L  V \  _ 

_  _._  _  -J  -      —      —  (       .    .   ..^  .- 


FIG.  2. — Castelnuovo-Valdarno  Plant.     Cross  Section  of  Switch  House. 


A-Generator  leads;  B-Circuit  breaker  6000  V.;  C-Potential  transformer;  D-Series  transformer; 
E-Selector  switch;  F-Generator  rheostat;  G  Transformers;  H-Blowers;  J-Circuit  breaker,  33,000  V  ; 
K-Series  transformer,  33,000  V.;  L-  and  N-Hook  switches;  M-Busbars,  33,000  V.;  O-Circuit  breaker, 
P-Series  transformer;  Q-Choke  coils;  R-Outgoing  line;  S-Ground-detector;  T-Horn  gaps;  U-Water 
rheostats;  V-Instrument  column;  W  Switchboard. 


ELECTRICAL  EQUIPMENT. 


179 


an 
aa 

aa 

ARRESTER) 


RAISING  TRANSFORMERS 
2200  TO  25,000  VOLTS  2200  TO  50,000  VOLTS 


GQOO  OOQOD 

^^^  ^— ^  ^**^-^  v_ s&    b^^"  ^--^  »^— -^  **^*^  ^ -A 


gag 
_ 


FIG.  3.— Plan  cf  Shawinigan  Falls  Plant. 


FIG.  4. — Shawinigan  Falls  Power  Plant. 


i8o 


HYDROELECTRIC    DEVELOPMENTS    AND    EXGEVEEREN'G. 


installed  between  the  oil  switches  and  the  bus,  being  on  the  outer  walls  and  imme- 
diately below  the  bus  bar  compartments,  which  are  above  on  floor  No.  3.  In  the 
center  of  floor  No.  3  are  the  low  tension  oil  switches,  the  two  oil  switches  correspond- 
ing to  a  generator  or  a  transformer  bank  being  arranged  back  to  back  and  facing 
their  corresponding  set  of  bus  bars. 

The  bus  bars  are  of  the  laminated  type,  consisting  of  flat  copper  bars  with 
expansion  joints,  and  supported  on  marble  slabs  set  on  edge,  which  in  turn  rest  on 
concrete  slabs,  forming  barriers  between  adjacent  bus  bars.  The  compartments 
formed  by  the  concrete  slabs  are  covered  by  insulating  fireproof  doors. 


FIG.  5. — Section  through  Generator  Room  and  Switchhouse,  Puget  Sound  Plant, 

Puyallup  River,  Washington. 

The  oil  switches  are  installed  in  brick  cells  with  soapstone  bottom  and  top  slabs 
and  doors.  Each  pole  of  a  switch  is  separated  from  the  others  by  brick  barriers. 
The  same  general  scheme  is  used  for  both  the  high  and  low  tension  disconnecting 
and  oil  switches,  except  that  only  one  set  of  high  tension  bus  bars  is  at  present 
installed,  provision  being  made  for  later  installation  of  the  second  set.  The  high 
tension  disconnecting  switches  and  current  transformers  are  on  floor  No.  5,  while 
the  high  tension  oil  switches  are  on  floor  No.  6.  Above  floor  No.  6  are  the  two 
outgoing  high  tension  line  towers,  in  the  north  end  of  which  are  the  high  tension 
lightning  arresters,  each  pole  being  separated  from  its  adjacent  pole  by  brick 
barriers  extending  the  full  length  of  the  arrester.  The  lines  emerge  from  the 
wire  tower  centrally  through  an  extra  heavy  3o-inch  sewer  tile  covered  by  a  glass 
plate. 


ELECTRICAL  EQUIPMENT. 


181 


SWITCHBOARDS. 

Object.  The  object  of  the  switchboard  is  to  collect  the  generated  current  for  the 
purpose  of  controlling,  measuring  and  distribution  of  same.  The  structure  and 
apparatus  mounted  on  same  should  be  fireproof,  and  so  arranged  that  easy  access 
may  be  had  to  all  parts  to  facilitate  inspection  and  repair.  The  arrangement  of 
the  apparatus  as  well  as  the  whole  switching  gear  must  be  simple  and  symmetrical 


FIG.  i. — 5o-cycle,  A.C.  and  D.C.  Switchboard,  Necaxa  Power  Plant,  Mexico. 

•  s 

to  prevent  as  much  as  possible  the  making  of  wrong  connections;  the  number  of 
instruments  and  protecting  devices  must  be  sufficient  to  secure  a  flexible  and  con- 
tinuous operation.  All  live  parts,  especially  those  of  high  potential,  must  be 
eliminated  from  the  front  of  the  switchboard.  When  installing  a  switchboard, 
provision  must  be  made  for  further  extension. 


182 


HYDROELECTRIC    DEVELOPMENTS    AND    ENGINEERING. 


In  laying  out  a  switchboard,  either  for  direct  or  alternating  current,  each  gene- 
rator or  machine  must  have  its  own  panel;  and  the  various  panels  for  the  same  type 
of  machines  should  be  in  a  separate  group;  according  to  American  practice,  for 
instance,  all  alternator  panels  should  be  together,  so  that  they  can  be  operated  from 
a  central  panel  when  working  in  synchronism. 

European  practice  is  virtually  the  same  as  the  above;  however,  in  a  very  recent 
installation  at  Brusio,  Switzerland,  each  generator  has  its  own  switchboard  directly 
opposite  the  generator.  When  the  various  generators  are  working  in  parallel  they 
are  controlled  from  a  single  instrument  column  in  front  of  the  exciter  switchboard 


o  o  o  o  6- 
o  o  o  o  <>• 

eo  o  'c  ! 


FIG.  2. — Westinghouse  Type  of  Panel  and 
Bench  Desk  Switchboard. 


FIG.  3. — General  Electric  Type  of  Panel  and 
Bench  Desk  Switchboard. 


in  the  middle  of  the  generating  room.  This  system  was  adopted  owing  to  the  great 
number  of  generators  installed.  The  generator  attendants  of  the  various  machines 
look  after  the  switchboards,  while  the  outgoing  feeders,  of  which  there  are  few,  are 
controlled  from  the  above  central  instrument  column. 

The  leads  from  generators  come  to  the  switchboard  from  beneath,  and  the  out- 
going feeders  usually  leave  from  the  top.  The  latter  particularly  must  be  well 
arranged  and  inconspicuously  placed. 

Types.  Switchboards  are  either  direct  or  remote  controlled.  For  voltages,  both 
alternating  and  direct  current,  the  switches  under  600  volts  are  direct  control,  while 
above  this  they  are  remote  control,  either  by  mechanical  devices,  such  as  bell  cranks, 
rods,  and  gears,  or  electrically  by  solenoids  or  motors.  There  are  a  few  installations 


ELECTRICAL  EQUIPMENT. 


183 


where  the  remote  control  system  is  operated  by  compressed  air,  but  such  a  system 
is  not  favored  in  present  practice. 

The  switchboards  installed  are  for  direct  and  alternating  current.  The  direct 
current  board  is  used  principally  for  controlling  excitation  and  the  alternating  for 
controlling  the  output  of  the  main  generators.  In  isolated  plants  for  small  industrial 
purposes,  having  no  long  transmission  lines,  a  common  switchboard  is  usually 
employed. 


FIG.  4. — Generator  Instrument  Columns,  Obermatt  Plant,  Luzerne,  Switzerland. 

Oerlikon  Co. 

Panel  Type.  Under  switchboards  one  finds  different  types,  such  as  panel,  pedestal 
or  column,  and  desk  or  benchboard.  The  panel  type  usually  has  mounted  on  it  the 
entire  switchboard  equipment.  In  many  instances  however,  in  recent  high  tension 
practice,  the  switchboard  has  only  on  the  front  the  meters  and  other  indicating 
instruments,  while  the  controlling  switches  are  placed  on  a  desk  or  bench  in  front  of 
the  panel  or  instrument  board.  These  boards  are  made  up  of  structural  steel  or 
pipe  frames  faced  with  white  or  blue  marble  or  slate  slabs.  The  marble  presents 
a  much  finer  appearance,  but  it  readily  shows  oil  stains  and  scratches,  and  if  the 
board  is  extended  at  any  future  time  it  is  difficult  to  match  the  panels.  Marble 


184 


HYDROELECTRIC    DEVELOPMENTS   AND   ENGINEERING. 


panels  are  chiefly  used  in  isolated  plants,  and  in  central  stations  in  Europe,  in  which 
case  the  panelboard  is  made  very  ornate. 

In  most  American  central  plants  and  substations  slate  with  dull  black  or  oil 
finish  is  used.  It  has  the  advantage  of  having  a  uniform  shade,  while  scratches  and 
oil  spots  are  readily  eradicated,  also  the  instruments  stand  out  in  a  bolder  relief. 
The  back  of  the  switchboard  for  low  tension  wiring  must  be  at  least  from  3  to  4 
feet  away  from  the  wall  and  thoroughly  braced  at  the  foot  and  top.  The  sizes  of  the 


FiG.  5. — Apparatus  in  back  of  aooo-K.W.,  6ooo-volt  Generator  Switchboard  Panel, 
Obermatt  Plant,  Luzerne,  Switzerland. 

panels  are  practically  standard.  For  instance,  the  General  Electric  Company's 
panel  consists  of  two  slabs,  the  lower  one  28  inches  high  and  the  upper  one  62  inches 
high,  the  width  being  24  inches.  The  power  section  of  the  Westinghouse  panel  is 
25  and  the  upper  65  inches.  The  Westinghouse  panel  is  sometimes  made  up  in 
three  sections,  the  lower  being  25,  the  middle  45,  and  the  top  20  inches,  the  upper 
being  primarily  made  for  the  mounting  of  a  circuit  breaker  to  enable  easy  removal 
in  case  of  repair  and  substitution. 


ELECTRICAL  EQUIPMENT. 


185 


Pedestal  or  Column  Type.  For  controlling  a  single  generator,  a  pedestal  or 
column  with  all  the  necessary  switches,  instruments,  etc.,  mounted  on  same  is 
employed.  In  most  cases,  they  are  arranged  in  front  of  the  feeder  panel  board,  with 
the  back  of  the  column  toward  the  generating  room,  so  that  the  operator  faces  the 
instruments  and  generating  room.  A  novel  arrangement  of  pedestal  and  columns 
has  been  adopted  by  the  Ontario  Power  Company,  where  they  are  arranged  in  a 
semi-circle,  and  easily  overlooked  from  the  desk  of  the  chief  operator. 


FIG.  6. — Cross  Section  of  Generating  Station  Switchboard  Arrangement,  with  Oil 
Switches  for  Remote  Control  by  means  of  Switchboard  Lever. 

Desk  or  Panel  Board.  The  desk  or  bench  board  are  chiefly  used  for  controlling 
the  main  oil  switches,  both  of  the  generator  and  outgoing  feeders.  They  are 
equipped  with  pilot  switches  and  lamps,  for  operating  the  main  circuit  breakers, 
field  switches,  field  rheostats,  governor,  motors,  etc.  These  benches  are  usually 
placed  in  front  of  the  instrument  board,  and  must  be  so  arranged  that  the  panel  of 
one  circuit  is  directly  behind  the  section  of  the  same  circuit  on  the  controlling  bench. 
To  further  facilitate  operation,  the  panel  and  control  bench  are  provided  with  card 
holders  or  name  plates  to  classify  the  groups.  In  addition,  dummy  bus  bars  are 
mounted  on  the  bench. 


1 86  HYDROELECTRIC    DEVELOPMENTS   AND   ENGINEERING. 


FIG.  7. — Instrument  and  Controlling  Bench  Lontsch  Hydroelectric  Plant, 
Switzerland,  Brown,  Boveri  &  Co. 


FIG.  8. — Typical  Exciter  or  D.C.  Generator  Panel  Arrangement  (Walker  Electric  Co.). 


ELECTRICAL  EQUIPMENT. 


187 


Where  it  is  desirable  that  the  switchboard  operator  should  command  a  view  of 
the  bench,  panel  board  and  the  generating  room  at  the  same  time,  the  bench  and 
board  are  placed  back  to  the  generating  room  with  the  board  elevated  on  posts,  with 
a  space  of  3  to  4  feet  between  the  top  of  the  bench  and  the  bottom  of  the  panel  board. 
In  some  of  the  European  plants,  the  designers  entirely  dispose  of  the  instrument 
board  by  mounting  the  instruments  and  the  controlling  devices  on  a  common  bench. 
It  is  common  practice  to  place  all  switchboards,  columns  and  benches  for  controlling 
generators  and  outgoing  feeders  on  galleries  or  mezzanine  floors. 


Wtmeterf 

Ammeter        -  "• 
Around  Detec'£b/s2a/nj& 
fffteostat  Handn'/tee/' 
feeder^  (Switches 


Generator  Switch 
Card  Holder 
Feeder  <5w/tc/i&$ 


FIG.  9. — Typical  D.C.  Combination  Panel  Switchboard. 

Direct  Current  Board.  The  direct  current  board  is  usually  made  up  of  one  panel 
for  each  exciter  unit,  containing  a  voltmeter,  ammeter,  main  and  field  switch,  circuit 
breaker  and  field  rheostat,  field  discharge  resistance,  also  equilizer  switch  for  parallel 
operation.  In  some  cases  the  latter  switch  is  placed  on  a  stand  near  the  machine  or 
mounted  on  the  machine  itself.  In  modern  practice  this  exciter  switchboard  is 
placed  on  the  main  operating  floor  near  the  exciters,  although  in  some  cases  they  are 
placed  on  the  operating  gallery  with  the  rest  of  the  control  apparatus.  The  circuit 
breakers  on  exciter  panels  must  be  non-automatic,  while  on  D.C.  generator  panels 
it  is  essential  that  they  are  automatic.  The  reason  for  this  is  that  the  exciter  current 
must  not  be  interrupted  except  when  the  main  unit  supplied  by  it  is  shut  down. 
For  ordinary  direct  current  distribution,  the  switchboard  is  divided  into  two  parts, 
the  generator  panels  and  the  feeder  panels.  The  above-mentioned  instruments  are 
mounted  on  the  generator  end,  while  on  the  feeder  end  each  feeder  panel  has  an 
ammeter,  integrating  wattmeter,  circuit  breaker  and  single  throw  knife  switch.  In 
many  cases  there  is  a  totalizing  watt  meter  connected  to  the  feeder  busses.  Where 
the  switchboard  is  provided  with  two  sets  of  busses,  the  feeder  panels  are  provided 


i88 


HYDROELECTRIC    DEVELOPMENTS    AND    ENGINEERING. 


with  double  throw  knife  switches,  so  as  to  connect  onto  either  bus.  Fig.  8  shows  a 
typical  arrangement  of  a  direct  current  generator  panel  with  only  one  set  of  busses 
and  an  equilizer  bus.  Another  type  of  D.C.  switchboard  equipment  is  seen  in  Fig.  9. 
It  will  be  observed  that  it  contains  the  necessary  instruments  for  the  generator  and 
switches  for  feeder  circuits,  as  the  feeder  circuits  do  not  contain  any  instruments 
it  is  a  typical  switchboard  for  an  isolated  plant. 

Low  Tension  A.C.  Boards.  —  In  isolated  plants  supplying  light  and  power  for 
manufacturing,  low  tension  three  phase  and  two  phase  is  usually  employed,  or  some 
modification,  for  instance,  a  4-wire,  3-phase  or  a  3-wire  2-phase.  The  voltage 
varies  from  200  to  600.  Fig.  10  shows  a  typical  layout  of  a  low  tension,  3-phase 


;•#)-  Wattmeter 
Voltmeter 
Potent/at 
Receptacle 


CtciterKheostat-*- 

Synchronizing 

•Receptacle 


Field 
Switcn 


Oil 

Switch 


H 24 H 


FIG.  10. — 480  and  6oo-volt,  3-phase  Generator  Power  with  Three  Main  Ammeters, 

General  Electric  Company. 


generator  panels  as  designed  by  the  General  Electric  Company.  These  switch- 
boards are  equipped  with  either  three  or  a  single  ammeter.  When  three  are  used, 
there  is  one  for  each  phase,  while  when  one  is  used,  it  is  assumed  that  the  phases 
are  balanced  so  that  one  meter  is  sufficient,  being  continuously  connected  to  one 
phase,  or  by  means  of  a  receptacle  and  plug,  connected  to  any  of  the  three  phases. 
All  alternating  current  boards  always  have  an  oil  switch  for  a  main  switch.  Where 
there  is  a  number  of  such  panels,  the  synchronizing  voltmeter  and  lamps  are  placed 
on  a  swinging  bracket  at  the  end  of  the  board,  while  each  panel  is  provided  only  with 
a  synchronizing  receptacle.  The  synchronizing  voltmeter  is  sometimes  replaced  by 
a  synchroscope  or  synchronism  indicator. 

Wagon  Panel.  A  novel  feature  in  switchboard  design,  in  use  only  a  few  years  on 
the  Continent  of  Europe,  is  the  Wagon  Panel  System.  Fig.  n  shows  a  carriage  as 
constructed  by  the  Allgemeine  Elektricitats-Gesellschaft,  Berlin.  It  consists  of  a 


ELECTRICAL  EQUIPMENT. 


UNIV.  OF  CA 


,O 


«po 


Jj 
i  ^ 


I    i.i 


FIG.  ii.— Wagon  Panel  Switchboard  of  the  Allgemeine  Elektricitats-Gesellschaft. 


FIG.  12. — Siemens-Schuckert  Wagon  Panel  Switchboard. 


190 


HYDROELECTRIC    DEVELOPMENTS    AND    ENGINEERING. 


carriage  running  on  small  wheels  upon  the  structural  steel  frame  of  the  switchboard 
and  carries  the  panel  with  all  the  instruments.  When  a  panel  is  to  be  removed,  a 
portable  wagon  is  backed  up  to  the  panel,  and  the  latter  is  pulled  out  (each  panel  is 
provided  with  two  handles)  onto  the  wagon  and  removed.  It  will  be  observed  that 
the  electrical  connections  do  not  have  to  be  disturbed  as  they  are  similar  to  a  knife 


FIG.  13. — Typical  Arrangement  of  i3,2oo-volt  Bus  Bars,  Electrically  Operated  Oil  Switches, 
and  Disconnecting  Switches  in  a  Three-Phase  Station,  General  Electric  Company. 


blade  switch,  that  is,  by  means  of  heavy  clips,  which  make  and  break  the  circuit  when 
the  carriage  is  rolled  in  or  out. 

In  the  Siemens-Schuckert  System,  the  entire  panel  and  its  equipment  is  built 
on  a  carriage  which  rolls  on  tracks  in  the  floor.  The  electrical  connections  are  made 
in  a  way  similar  to  the  above.  The  wagon  of  each  system  is  so  provided  with 


ELECTRICAL    EQUIPMENT.  191 

locking  switches,  that  it  cannot  be  withdrawn  while  the  panel  is  in  operation,  which 
is  particularly  essential  for  high  tension  switchboards. 

In  the  Siemens-Schuckert  system  the  entire  panel  and  its  equipment  is  built 
on  a  carriage  which  rolls  on  tracks  in  the  floor.  The  electrical  connections  are  made 
in  a  way  similar  to  the  above.  The  wagon  of  each  system  is  so  provided  with  lock- 
ing switches  that  it  cannot  be  withdrawn  while  the  panel  is  in  operation,  which 
is  particularly  essential  for  high  tension  switchboards. 

The  principal  advantage  of  this  "  Wagon-panel  System  "  is  that  a  panel  can  be 
withdrawn  for  inspection  and  repairs  and  that  a  reserve  panel  can  eventually  replace 
an  old  one  without  disturbing  the  operation  of  the  remaining  units.  Thus  the 
danger  otherwise  encountered  in  making  repairs  on  the  switchboard  is  eliminated. 

High  Tension  Alternating  Current  Boards.  High  tension  switches  are  of  the 
remote  control  type,  that  is,  the  switches  are  located  at  a  distance  from  the 
switchboard,  so  that  the  switchboard  contains  only  low  tension  current  apparatus 
used  for  operating  the  high  tension  switches,  thus  eliminating  the  danger  of  high 
tension  apparatus  from  the  operator.  The  oil  switches  are  frequently  mounted  in 
masonry  cells  and  operated  either  by  motor  or  solenoid;  and  as  they  have  no  mechani- 
cal connections  with  the  switchboard,  they  may  be  located  at  any  convenient  place. 
The  motors  or  solenoids  for  operating  the  switches  are  mounted  on  top  of  the  oil 
compartments  and  usually  operated  by  no  or  220  volt  direct  current.  In  some  cases 
the  current  for  operating  the  switches  is  taken  from  the  exciter  busses,  while  in 
others  a  storage  battery  is  maintained  for  the  purpose. 


SWITCHBOARD    EQUIPMENT. 

Volt  and  Ammeters.  The  voltmeters  and  ammeters  are  either  of  the  round, 
sector  dial  or  of  the  edgewise  type.  The  latter  are  frequently  installed  in  such  a  way 
that  they  may  be  readily  removed  by  lifting  them  out  of  the  swtichboard  slab.  In 
some  recent  European  plants  the  instruments  are  set  so  that  the  faces  are  flush 
with  the  panel.  Instruments  are  always  placed  on  the  generator  side  of  the  line 
transformers.  Where  the  voltage  is  higher  than  150,  potential  transformers  are 
required  in  connection  with  the  voltmeter.  For  ammeters  greater  than  5  amperes 
series  transformers  are  necessary,  and  for  capacities  greater  than  800  amperes  the 
series  transformers  are  so  arranged,  to  slip  over  the  bus  bar  or  cable. 

Wattmeter.  Wattmeters  are  used  to  indicate  the  output  of  a  generator.  They 
are  made  both  indicating  and  recording.  The  former  gives  only  the  momentary 
output,  while  the  latter  gives  a  continuous  record.  With  Westinghouse  wattmeters, 
except  those  for  5  amperes  and  not  over  400  volts,  series  transformers  are  required. 
Where  the  alternations  exceed  3000  and  the  voltage  200,  shunt  or  potential  trans- 
formers are  required.  For  the  General  Electric  Company's  Thomson  Induction 
Wattmeter  a  series  and  potential  transformer  are  necessary  only  when  the  amperes 
exceed  150  and  the  volts  1150.  Fig.  i  shows  the  wattmeter  connections  with  and 
without  a  current  transformer. 


192 


HYDROELECTRIC    DEVELOPMENTS    AND    ENGINEERING. 


Synchronizing.  To  facilitate  the  synchronizing  of  generators  suitable  instru- 
ments must  be  installed.  They  consist  usually  of  two  lamps  and  a  bell,  so  that  when 
the  alternators  are  out  of  step  this  condition  is  indicated.  The  lamps  are  of  dif- 
ferent colors,  green  indicating  that  the  machine  is  running  too  slow  and  red  that  it  is 
too  fast.  An  instrument  which  indicates  this  condition  more  readily,  that  is,  indicat- 
ing how  much  the  generator  is  out  of  step,  has  been  put  on  the  market  in  recent 
years  under  the  name  of  synchroscope  and  synchronism  indicator. 

The  attendant,  when  synchronizing  a  generator,  operates  a  pilot  switch  con- 
trolling the  motor  on  the  water  wheel  governor.  Thus  when  the  synchroscope  indi- 
cates that  the  incoming  machine  is  too  slow,  he  turns  the  pilot  switch  so  that  the  motor 
will  allow  the  governor  to  increase  the  speed  of  the  turbine  until  synchronism  is 
reached;  and  the  generator  is  thrown  on  the  bus. 

To  minimize  the  time  lost  in  synchronizing,  an  automatic  synchronizer  has  been 
placed  on  the  market.  When  using  this  instrument  the  attendant  has  only  to  put 
it  in  operation  and  adjust  the  speed  of  the  incoming  generator.  At  the  first  instance 
of  synchronism  the  instrument  will  automatically  throw  the  machine  on  the  busses. 


FIG.  i. — Connections  of  Two  Wire  Induction  Wattmeters. 


Power  Factor  Meter.  In  most  alternating  installations  the  power  factor  meter 
is  of  great  value.  It  is  built  for  single  and  polyphase  circuits  and  for  3000 
and  7200  alternations  and  in  standard  sizes  up  to  2000  volts  and  2000  amperes.  It 
indicates  directly  and  accurately  results  which  otherwise  can  only  be  reached  by 
computation  from  readings  which  if  not  taken  simultaneously  may  lead  to  error. 

The  dial  of  the  power  factor  meter  is  divided  into  four  quadrants,  each  being 
marked  from  o  to  100.  These  figures  represent  percentages  which  would  be 
obtained  by  dividing  the  "  true  watts  "  in  the  circuit  (as  indicated  by  a  wattmeter) 
by  the  "  apparent  watts  "  (the  product  of  volts  and  amperes).  The  angular  position 
of  the  pointer  at  any  moment  also  indicates  the  angular  difference  in  phase  between 
current  and  voltage.  The  upper  half  of  the  dial  indicates  the  power  factor  for 
lagging  or  leading  currents  when  power  is  being  delivered  in  one  direction,  and  the 
lower  half  gives  similar  indications  for  power  delivered  in  the  opposite  direction. 
In  this  way  the  power  factor  meter  may  serve  to  show  a  reversal  of  the  direction  of 
power  on  the  line. 

In  the  operation  of  rotary  converters  this  instrument  finds  important  uses;  it 
simplifies  the  adjustment  of  field  strength,  either  for  minimum  armature  current  or 


ELECTRICAL    EQUIPMENT. 


193 


to  produce  some  desired  effect  on  the  system  as  a  whole.  The  poor  power  factors 
resulting  from  heavy  inductive  loads  may  often  be  much  improved  or  entirely 
neutralized  by  proper  field  adjustment  of  rotary  converters  and  other  synchronous 
apparatus.  With  generators  running  in  parallel  the  proper  distribution  of  the  load 
can  be  checked,  and  in  many  cases  the  number  of  ammeters  required  may  be 
considerably  reduced  by  the  use  of  the  power  factor  meter. 


FIG.  2. — Motor  Control  Rheostat  for  Field  Excitation  of  Main  Generator,  Westinghouse 

Electric  Manufacturing  Company. 

Frequency  Meter.  To  eliminate  calculations  necessary  to  ascertain  the  frequency 
of  a  generator,  and  incidentally  the  revolutions,  a  frequency  meter  may  be  employed. 
It  may  be  mounted  on  the  switchboard  and  occupy  the  same  space  as  any  other 
indicating  instrument.  It  is  built  for  any  frequency  with  a  +  or  --  variation 
of  25  per  cent  of  the  normal.  When  used  on  circuits  exceeding  100  volts  a  shunt 
transformer  is  required. 

Rheostats.  Rheostats  in  generating  stations  are  used  for  controlling  the  excitation 
of  generator  fields.  The  rheostats  for  the  exciters,  being  small,  are  mounted  on  the 
back  of  the  exciter  switchboard  and  in  most  cases  are  hand  controlled,  while  those 
for  the  main  generators  are  of  large  size,  and  have  to  be  placed  in  compart- 
ments which  must  be  well  ventilated.  These  large  rheostats  are  always  remote 
controlled,  either  by  shaft  and  gearing,  much  used  in  Europe,  or  by  motors,  common 
American  practice.  The  pilot  switches  for  controlling  same  are  mounted  on  the 
control  bench. 


194 


HYDROELECTRIC    DEVELOPMENTS    AND   ENGINEERING. 


Illumination.  The  switchboard  proper  must  be  suitably  illuminated  so  that 
the  condition  of  switches  can  at  all  times  be  readily  seen,  also,  illuminate  the  faces 
of  the.  different  meters.  Some  of  the  meters  have  opal  glass  scales  and  are  illumi- 
nated from  the  rear,  making  it  possible  to  read  the  indication  from  a  distance  or  in 
otherwise  insufficient  light.  The  lamps  are  inclosed  in  a  compartment  separate 


FIG.  3. — Remote  Control  Hand  Operated  Rheostats  for  Field  Excitation  of  the  Main  Generator, 

Oerlikon  Company. 

from  the  working  part  of  the  meter.  Where  meters  with  illuminated  dials  are  not 
installed,  a  system  of  incandescent  lamps  is  mounted  on  the  switchboard  proper 
or  suspended  in  front  of  same,  and  for  either  alternating  or  direct  current,  but 
preferably  of  both  to  meet  emergency. 


WIRING   DIAGRAM. 

Systems.  All  power  plants,  whether  small  or  large,  depending  on  continuous 
operation,  must  have  a  double  set  of  bus  bars,  or  the  equivalent.  The  leads  from 
the  generators  to  the  bus  bars  must  be  so  provided  with  switches  that  current  can 
be  thrown  on  to  either  of  the  systems.  For  small  plants,  where  there  is  a  light  and 
power  load,  one  bus  may  be  kept  separately  for  light  and  the  other  for  power.  To 
increase  the  flexibility  of  the  system,  the  feeders  to  and  from  the  bus  bars  must  be 


ELECTRICAL    EQUIPMENT. 


195 


196 


HYDROELECTRIC    DEVELOPMENTS   AND   ENGINEERING. 


such  that  either  or  both  light  and  power  can  be  drawn  from  either  of  the  busses. 
The  leads  between  generator  and  bus  bars  must  be  provided  with  a  main  switch,  so 
that  each  individual  unit  may  be  cut  out  without  affecting  the  operation  of  the 
remainder  of  the  plant.  An  additional  safeguard  for  continuous  operation  is  to  place 
sectionalizing  switches  in  the  bus  bars. 

In  high  tension  plants  where  oil  switches  are  used,  section  or  hook  switches  must 
be  placed  on  either  side  of  same,  so  that  they  may  be  isolated  for  inspection  and 


High  Voltage  Feeders 
ill  ill 


Low  Voltage  Feeders 


rtt     ttt     tt»     ttt     ttt 


ttt 


III      111      III      til      111      Ui 

II  1        TTT        TTT        TTT        TTT 


&,&&&&&, 

Generators  laoooVoffs 

FIG.  i. — Wiring  Diagram  of  Power  Circuits,  Ontario  Power  Company. 


repair.  Where  transformers  are  installed  either  for  stepping  up  or  stepping  down, 
particularly  where  there  are  a  number,  it  is  advisable  to  have  a  bus  on  the  outgoing 
feeder  side.  In  American  practice  the  double  bus  bar  system  for  outgoing  feeders 
is  seldom  used,  but  will  be  found  to  a  great  extent  in  Swiss  practice,  in  the  form  of  a 
ring  system. 

Fig.  i  shows  the  general  arrangement  of  the  wiring  diagram  of  the  Ontario 
Power  Company's  plant.1  It  will  be  observed  that  the  wiring  system  is  simple,  yet 
as  flexible  as  possible. 

1  The  Electrical  Plant  of  the  Ontario  Power  Company,  by  V.  G.  Converse.  Canadian  Electrical  Asso- 
ciation, Niagara  Falls,  June,  1906. 


ELECTRICAL    EQUIPMENT. 


197 


The  generators  can  be  thrown  on  either  of  the  two  low  tension  (12,000  volt) 
busses,  and  the  transformers  can  draw  from  either  of  same.  It  will  also  be  noticed 
that  both  high  (62,000  volt)  and  low  tension  busses  are  well  provided  with  section 
switches.  The  local  distribution  (12,000  volts)  may  draw  current  from  either  of 
the  two  low  tension  busses. 

A  somewhat  more  simplified  wiring  system  is  that  of  the  Necaxa  power  plant, 
Mexico  (Fig.  2).  There  is  only  a  single  low  tension  (4000  volt)  bus  bar  system. 


40  000  Vollt  outgoing  Li: 


DIAGRAM  OF  CONNECTION 
OF 

NECAXA  POWER  PLANT 

FOR 
MEXICAN  LIGKT  ANO  POWER  COMPANY 


000  Volts  Fui  in  I!  Switch 


\  V  \  \  CO  000  Volts  Di&om.  Switch 

_« i^N^i— J^— i— — — ^^-™— "^— —  <"  MO  v»"< 


VW|«W^  VW^VVA  VWWWW  VWAWtfWV  /WW1/VWW  y 

Q  /D  .U  U  i.OOOV^Fo^.HS.itoh 


acdioulizing  Svitcho 


FIG.  2. — Wiring  Diagram  of  the  Necaxa  Power  Plant,  Mexico. 


The  current  from  the  generators  may  be  thrown  upon  same  or  directly  on  the 
transformers.  This  would  mean  that  the  transformers  can  draw  from  the  bus  bars 
irrespective  of  the  operation  of  their  own  generator.  There  is  but  one  high  tension 
(60,000  volt)  bus  bar  system. 

A  wiring  diagram  in  which  the  generator  or  low  tension  bus  has  been  eliminated, 
although  the  plant  is  of  large  capacity,  is  that  of  the  Urfttalsperre,  Germany.  Each 
5ooo-volt  generator  feeds  through  a  fuse  directly  to  its  transformer.  The  reason 
for  this  arrangement  is  that  if  a  transformer  is  out  of  commission  the  particular 


198 


HYDROELECTRIC    DEVELOPMENTS    AND    ENGINEERING. 


ELECTRICAL    EQUIPMENT. 


199 


generator  is  shut  down  and  vice  versa.  The  high  tension  side  is  tied  together  with 
a  ring  bus  bar  system,  the  ends  of  which  are  connected  through  choke  coils  (see 
Fig.  4).  Between  the  transformer  and  bus  bar  are  automatic  oil  switches.  Each 
outgoing  feeder  is  provided  with  an  automatic  oil  switch,  choke  coil,  and  three-pole 
tie  switch.  The  outgoing  feeders  are  doubly  interconnected  with  tie  switches,  so 
that  in  fact  two  ring  systems  are  secured  on  the  high  tension  side.  The  whole  is 
amply  protected  by  lightning  arresters. 


WSt 


FIG.  4. — Wiring  Diagram  of  the  Urfttalsperre  Plant,  Heimbach,  Germany. 


G  =  Generators. 

T  =  Transformers. 
t  =  Section  Switches. 
WSt  =  Waterflow  Grounders. 
WW=  Water  Rheostats. 


OW  =  Oil  Rheostats. 
E  =  Earth. 
S  =  Circuit  Breaker. 
s  =  Fuses. 
D  =  Choke  Coils. 


Considering  the  protection  and  particularly  the  flexibility  of  the  high  tension 
side,  it  seems  strange /that  the  low  tension  side  should  be  so  rigidly  connected.  It 
will  be  readily  seen  that  this  plant  can  be  seriously  handicapped  when  a  transformer, 
a  generator,  and  a  turbine  of  different  groups  are  out  of  commission. 

Swiss  power  plants  employ  either  the  double  bus  bar  or  ring  system.  Either  one 
in  itself  is  very  intricate.  A  good  example  of  this  kind  is  given  in  Fig.  5,  and  is  that 
of  the  Obermatt  plant,  Lucerne.  It  supplies  light  and  power  for  various  pur- 
poses, for  which  four  2ooo-HP.  generators  serve;  a  fifth  generator  used  exclusively 
for  street  railway  purposes  (located  in  the  left  hand  of  the  wiring  diagram)  is  inde- 
pendent of  the  rest  of  the  plant.  As  these  four  generators  supply  three  phase  for 
power  or  single  phase  for  lighting  a  certain  section,  there  are  two  ring  bus  bar 


1-4-1 -"* 


FIG.  5. — Wiring  Diagram  of  the  Obermatt  Plant,  Switzerland. 


ED  - 
GB  - 
DW- 

T 
RT  - 

M 
AB  - 

R 

AU  • 
KA  - 
MA 
OA 


Exciter.  MO 

Railway  Generator  U 

Three-phase  Alternators.  VU 
Transformers.  D 

Reserve  Transformers.  TS 
Measuring  Transformers.  S 
Storage  Battery.  A 

Regulator.  ST 

Cut  out  Switch  V 

Carbon  Cut-out  Switch.  DV 
Overload  Switch  SV 

SecUonalizing  Switch.        GV 


Overload  Oil  Switch.  W '-- 

Double  Throw  Switch.  L  -- 

Voltmeter  Switch.  SL  -- 

Double-cell  Switch.  WW '- 

Disconnecting  Switch.  B  •• 

Fuse.  F  •• 

Ammeter.  /  = 

Series  Transformer.  WA  •• 

Voltmeter.  E  •• 

Double  Voltmeter  Z  = 

Static  Voltmeter.  ZO  : 

Bus  Bar  Voltmeter  ZR  •• 


Wattmeter. 

Phase  Lamp. 

Signal  Lamp. 

Water  Rheostats. 

Lightning  Arrester. 

Lightning  Arrester. 

Choke  Coils 

Water  Flow  Grounders. 

Earth  Plate 

Three  phase  Ammeter 

Overload  Oil  Circuit  Breaker 

Time  Relays 

200 


ELECTRICAL    EQUIPMENT. 


201 


Direct-Current  Bui  Ban 

FIG.  6. — Complete  Wiring  Diagram  of  a  Single  Generator  and  Step-up  Transformer. 


systems  on  the  low (6000  volt)  tension  as  well  as  the  high  (27,000  volt)  tension  side. 
The  two  bus  bar  systems  on  either  side  consist  of  a  single  phase  and  three  phase 
group. 

BUS   BARS. 

Bus  bars  are  made  up  of  cables  or  flat  bars  of  copper  or  aluminum.  Flat  bars, 
for  mechanical  reasons,  are  preferable  to  round  ones,  as  connections  are  readily 
made.  Where  the  bus  bars  are  of  short  length  they  may  be  made  of  uniform 
section  throughout.  However,  where  the  bus  bars  extend  over  the  entire  length  of 
the  generating  room,  as  is  frequently  the  case  for  sake  of  economy,  the  bus  bars 
are  flat,  each  of  across  section  area  necessary  for  one  generator;  thus  where  a 
generator  lead  joins  it  an  additional  bus  bar  section  is  added. 

Size  of  Bus  Bars.  The  size  of  the  bus  bar  is  determined  by  the  number  of 
amperes  it  has  to  carry.  From  700  to  800  amperes  per  square  inch  of  copper  is  usually 
chosen  as  a  safe  value.  For  electrical  reasons  flat  bars  are  better  than  round  ones, 


2O2 


HYDROELECTRIC    DEVELOPMENTS    AND    ENGINEERING. 


because  they  present  a  greater  radiating  surface  thus  keeping  the  resistance  from 
increasing  due  to  heating.  This  is  also  a  reason  in  favor  of  open  bus  bar  com- 
partments. 

If  aluminum  is  used  in  place  of  copper,  the  bus  bars  must  have  a  cross  sectional 
area  of  1.66  times  that  of  copper,  for  equivalent  electrical  conductivity. 

Closed  Compartments.  Similar  to  the  arrangement  for  high  tension  oil  switches, 
the  bus  bars  and  disconnecting  switches  are  also  placed  in  masonry  compartments. 
The  compartments  are  made  either  of  brick  or  concrete,  and  are  entirely  closed 


FIG.  i. — Three-Deck  Oil  Circuit  Breaker 
and  Bus  Bar  Structure.  Two  Sets 
of  Bus  Bars. 


%%%^#3^^ 


FIG.  2. —  Typical  American  Arrangement  of 
Oil  Circuit  Breakers  and  Bus  Bars  for 
15,000  volts  or  less. 


(having  access  through  openings)  or  else  open  altogether.  With  high  tension 
busses,  where  space  is  limited,  the  former  arrangement  is  preferable.  The  open- 
ings to  the  compartments  are  about  15  inches  square  and  are  staggered.  As  a  means 
of  protection  for  inspectors  and  repair  men  they  are  best  closed  with  a  sheet  steel 
door. 

Open  Compartments.  Where  space  is  ptenty,  which  is  usually  the  case  with 
hydraulic  plants,  the  entire  front  of  the  bus  bar  compartment  may  be  left  open.  The 
insulators  for  carrying  the  busses  are  mounted  either  on  the  back  wall  or  shelves. 


ELECTRICAL    EQUIPMENT. 


203 


FIG.  3. — 6ooo-volt  Bus  Bar  Room,  Obermatt  Plant,  Luzerne,  Switzerland. 


FIG.  4. — 8ooo-volt  Oppen  Bus  Bar  Chamber,  Lontsch  Plant,  Switzerland. 


204  HYDROELECTRIC    DEVELOPMENTS   AND   ENGINEERING. 

In  order  to  eliminate  posts  or  partitions  for  carrying  the  shelves,  the  latter  are  best 
made  of  reinforced  concrete,  giving  an  unobstructed  view  of  the  busses  and  also 
facilitating  construction,  inspection,  and  repair.  Fig.  4  gives  an  illustration  of  open 
bus  bar  construction  at  the  Lontsch  plant,  Switzerland.  The  busses  carry  80,000 
volts.  Another  view  of  Swiss  practice  is  seen  in  Fig.  3  where  no  shelves  between 
individual  phases  are  used.  There  is  only  one  shelf  which  separates  the  single  phase 
from  the  three  phase  busses  (6000  volts.) 

OIL   SWITCHES. 

General  Remarks.  In  modern  switchboard  engineering  one  will  find  the  most 
contradictory  practice.  Oil  switches  for  600  volts  are  designed  and  installed  on  the 
back  of  the  switchboard,  operated  by  a  single  lever,  while  on  the  other  hand  they  are 
remote  controlled.  Again,  switches  for  10,000  volts  are  mounted  directly  on  the  back 
of  the  switchboard.  Also,  with  6ooo-volt  switches,  the  oil  chambers  for  the  indi- 
vidual phases  are  placed  in  large  and  very  expensive  masonry  cells,  the  access  to  which 
is  well  protected  by  specially  designed  fireproof  doors;  while  on  the  other  hand, 
with  5o,ooo-volt  oil  switches,  all  phases  are  placed  in  a  single  sheet  metal  tank, 
unprotected  and  exposed  to  view.  In  addition  to  this,  the  former  is  operated  by 
motor  or  solenoid,  the  latter  by  lever  and  rods.  The  difference  between  America 
and  Europe  in  this  practice  is  clearly  indicated  in  accompanying  illustrations. 

To  go  still  further  in  citing  the  difference  existing  in  American  practice,  there  are 
60,000  and  80,000  volt  oil  switches  in  operation  which  have  the  phases  in  separate 
sheet  steel  tanks  exposed  to  view,  being  entirely  unprotected  by  masonry  construc- 
tion, as  is  done  in  the  6ooo-volt  switches.  Even  120,000- volt  oil  switches  of  the 
former  type  are  advocated. 

From  the  foregoing  contradictory  practice  it  will  be  observed  that  arguments 
about  the  danger  to  the  operating  force  from  exposed  high  tension  apparatus  are 
without  reason,  particularly  if  one  bears  in  mind  that  practice  has  proven  that 
220  volts  may  kill  as  readily  as  30,000  volts  and  higher.  It  is  evident  from  the 
above  that  much  could  be  saved  on  first  cost,  maintenance,  and  floor  space  in  the 
design  of  modern  oil  switches. 

Types.  Oil  switches  up  to  5000  volts  are,  according  to  American  practice,  of  the 
self  contained  oil  type;  they  are  made  up  of  a  sheet  steel  tank  with  partitions  to 
separate  the  phases,  and  lined  with  insulating  material.  The  lining  and  partitions 
are  frequently  made  of  wood.  The  contacts  of  the  switch  are  in  oil,  so  that  the  make 
and  break  are  made  submerged.  The  phases  are  usually  equipped  with  multiple 
break  contacts,  thus  securing  a  great  current  breaking  capacity. 

The  practice  regarding  the  operation  of  high  voltage  switches  varies  greatly.  In 
some  cases  2300-volt  switches  are  operated  by  remote  control  levers,  rods,  and  bell 
cranks,  or  by  motors  or  solenoids.  In  Swiss  practice,  io,ooo-volt  switches,  in  some 
instances,  are  mounted  on  the  back  of  the  switchboard  and  operated  by  hand  levers 
as  seen  in  Fig.  i.  Frequently  in  American  practice  switches  larger  than  5000  kilowatts 
capacity,  the  phases  are  submerged  in  individual  oil  tanks  and  have  multiple  break 


ELECTRICAL    EQUIPMENT. 


205 


FIG.  i. — Oerlikon  io,ooo-volt  Air  Break  Switch. 


FIG.  2. — Oerlikon  3o,ooo-volt,  3oo-ampere,  Solenoid  Controlled  Circuit  Breaker. 


2O6 


HYDROELECTRIC    DEVELOPMENTS    AND    ENGINEERING, 


contacts.     Each  pole  of  these  oil  switches  is  inclosed  in  a  separate  fireproof  structure 
made  of  brick  or  concrete. 

The  use  of  soapstone  is  not  essential  and  it  must  be  borne  in  mind  that  it  readily 
absorbs  oil.  The  doors  to  the  tank  compartments  are  either  asbestos  fiber,  slate 
slabs,  or  wire  glass,  and  are  held  in  place  by  clamps,  or  hung  from  the  top  of  the 
compartment.  It  is  common  practice  on  the  continent  of  Europe  to  have  the  poles 
of  all  phases  for  any  voltage  in  one  sheet  metal  tank.  In  some  cases,  however,  phases 
are  placed  in  small  separate  oil  tanks  and  not  separated  by  partition  walls.  The 


FIG.  3.  —  Westinghouse  n,ooo-volt,  6oo-ampere,  Remote  Solenoid  Controlled,  3-pole  Oil 

Switch. 


oil  tanks  are  grouped  and  mounted  on  iron  frames  in  compartments  of  reinforced 
concrete  and  always  exposed  to  view.  Switches  or  circuit  breakers  of  this  construc- 
tion have  been  installed  up  to  50,000  volts  normal  capacity  (see  Fig.  2). 

American  switches  for  60,000,  80,000,  100,000  volts,  and  even  higher  are  designed 
on  the  same  principle  as  those  for  30,000  volts.  They  are  either  top  or  bottom 
connected.  The  bottom  connected  switch  is  arranged  with  two  pots  forming  one 
pole  of  the  switch  mounted  on  a  common  horizontal  platform,  and  is  usually  operated 
by  a  motor.  This  type  of  switch  requires  a  comparatively  small  amount  of  oil,  and 
has  a  further  advantage,  that  the  circuit  is  opened  in  two  independent  receptacles 


ELECTRICAL    EQUIPMENT. 

per  phase.  According  to  Hayes/  the  exposed  metal  parts  of  this  switc 
tank  and  bare  terminals  below,  necessitate  the  inclosing  of  the  switch  in  a  masonry 
structure  for  the  protection  of  the  attendant.  Doors  are  provided  for  each  compart- 
ment of  the  structure,  to  permit  the  ready  inspection  of  the  tanks,  etc.,  but  the  removal 
or  breaking  of  a  door  leaves  these  live  metal  parts  a  source  of  danger.  Such  switches 


FIG.  4. — High  Tension  Oil  Switch  Compartment,  Ontario  Power  Company. 

have  been  installed  in  the  6o,ooo-volt  circuit  of  the  Electrical  Development  Corn- 
pan)'  of  Toronto  at  Niagara  Falls. 

The  top  connected  switches  are  usually  solenoid  operated,  and  the  oil  tanks  are 
of  sheet  metal.  The  two  stationary  contacts  forming  each  pole  are  located  near  the 
top  of  the  oil,  where  sediment  cannot  settle.  The  contacts  are  separated  by  barriers, 


Switchboard  Practice  for  Voltages  of  60,000  and  upwards,  by  S.  Q.  Hayes       Am.  Inst.  E.  E.,  June, 


1907. 


208 


HYDROELECTRIC    DEVELOPMENTS    AND    ENGINEERING. 


as  though  each  contact  were  in  a  separate  tank.  This  type  is  usually  installed  without 
being  encased  in  masonry  compartments;  however,  the  tanks  and  all  the  mechanism 
must  be  properly  grounded  for  the  protection  of  attendants.  In  the  distributing 


FIG.  5.  —  3o,ooo-volt,  5o-ampere,  Remote  Motor  Control,  3-pole  Oil  Switch, 
General  Electric  Company. 

station  of  the  Ontario  Power  Company  types  of  this  switch  are  installed  for  62,000 
volts.  Both  switches,  of  course,  can  be  installed  as  circuit  breakers,  as  practically 
all  high  tension  switches  have  this  provision,  and  can  be  arranged  to  work  with  a 
scheme  of  inclosed  or  open  wiring.  The  bottom  connected  switch  is  essentially 


ELECTRICAL    EQUIPMENT. 


209 


designed  for  plants  where  the  wiring,  bus  bars,  etc.,  are  placed  in  separate  com- 
partments, while  the  top  connected  breaker  is  designed  for  plants  where  the  wiring 
is  overhead. 

Circuit  Breakers.   A  high  tension  oil  circuit  breaker  is  nothing  more  than  an  oil 
switch  provided  with  an  automatic  opening  device.     The  purpose  of  the  circuit 


FIG.  6. — 11,000  and  5o,ooo-volt  Switches  and  Substation,  Castellanza,  Italy. 

breakers  is  to  protect  the  generators  and  transformers  from  overloads,  reversal  of 
line  current,  and  excess  voltage,  for  which  purpose  (a)  overload  relays,  (&)  reverse 
current  relays,  (c)  over-voltage  relays,  are  installed. 

(a)  Overload  Relays.  Overloads  in  most  cases  are  caused  by  short  circuits  on 
the  line.  The  common  practice  is  to  maintain  the  short  circuit  and  burn  it  out. 
There  are  cases,  however,  where  the  short  circuit  cannot  be  burned  out,  and  to 
maintain  it  would  damage  the  line.  To  prevent  long  and  excessive  shorts  from. 


210  HYDROELECTRIC    DEVELOPMENTS    AND   ENGINEERING. 


FIG.  7.— 88,ooo-volt  Top-connected  Circuit  Breaker  with  Sheet-Metal  Tanks. 


FIG.  8.— Siemens-Schuckert  35,ooo-volt  Remote  Control          FIG.  9. — Siemens-Schuckert  High 
Switch  with  two  Current  Blowouts.  Oil  Tank  removed.  Tension  Time  Relay. 


ELECTRICAL    EQUIPMENT.  211 

damaging  the  line,  the  circuit  breakers  are  provided  with  an  overload  relay,  which 
will  cause  them  to  open  in  a  certain  set  time  after  the  short  is  established.  The 
time  varies  usually  from  one  to  five  seconds,  depending  upon  the  setting  of  the  time 
limit  of  the  relay. 

(b)  Reverse  Current   Relays.     The  reversals  of  current    are  caused  chiefly  by 
synchronous  apparatus  connected  on  the  line,   such   as  synchronous  motors  and 
rotary  converters.     Cases  sometimes  arise  that  these  machines  instead  of  absorbing 
power  will  pump  it  back,  and  when  this  happens  there  is  usually  trouble,  especially 
if  there  are  underground  conduits  in  the  system.     To  prevent  any  damage  from  this 
source,  the  power  house  circuit  breakers  are  provided  with  reverse  current  relays, 
which  cause  the  breaker  to  open  upon  reversal  of  line  current. 

(c)  Overload  Voltage  Relays.     The  over-voltage  relay  causes  the  breaker  to  open 
upon  excess  of  normal  voltage,  due  to  over-excitation  or  poor  line  regulation.     The 
former  difficulty  is  under  the  control  of  the  operator,  while  the  latter  is  under  the 
control  of  the  designing  engineer  and  may  be  eliminated.     These  relays  are  not 
extensively  used  on  high  tension  systems. 


BIBLIOGRAPHY. 

THE  THEORY  AND  CALCULATION  OF  ALTERNATING  CURRENT  PHENOMENA.    Charles  P.  Steinmetz, 

1908. 

GENERAL  LECTURES  ON  ELECTRICAL  ENGINEERING.     Charles  P.  Steinmetz.     1908. 
ALTERNATING  CURRENT  ENGINEERING  PRACTICALLY  TREATED.     E.  B.  Raymond.     1905. 
ALTERNATING  CURRENT  MACHINERY.  «  William  Esty.     1907. 
ALTERNATING  CURRENT  MACHINES.    Samuel  Sheldon  and  H.  Mason.     1908. 
EXPERIMENTS  WITH  ALTERNATING  CURRENT  OF  HIGH  POTENTIAL  AND  HIGH  FREQUENCY.    N.  Tesla. 

1904. 

HIGH  SPEED  ELECTRICAL  MACHINERY.    H.  M.  Hobart  and  A.  G.  Ellis.     1908. 
DYNAMOS,  MOTORS,  ALTERNATORS,  AND  ROTARY  CONVERTERS.     G.  Knapp.     1902. 
POLYPHASE  ELECTRIC  CURRENTS  AND  ALTERNATE-CURRENT  MOTORS.    S.  P.  Thompson.     1903. 
THE  INSULATION  OF  ELECTRIC  MACHINERY.    H.  Turner  and  H.  M.  Hobart.     1907. 
PRACTICAL  DYNAMO  AND  MOTOR  CONSTRUCTION.    A.  W.  Marshall.     1907. 
ELEMENTARY  PRINCIPLES  OF  CONTINUOUS-CURRENT  DYNAMO  DESIGN.     H.  M.  Hobart  and  H.  F. 

Parshall.     1908. 

THE  MANAGEMENT  OF  ELECTRICAL  MACHINERY.     F.  B.  Crocker  and  S.  S.  Wheeler.     1907. 
DYNAMO-ELECTRIC  MACHINERY.     F.  B.  Crocker.     1907. 
TROUBLES  OF  CENTRAL  STATION  SWITCHING  APPARATUS  AND  METHODS  OF  HANDLING  THEM.     C.  F. 

Conrad.     Electrical  World,  Aug.  i,  1908. 

EXTRA-HIGH-PRESSURE  IRONCLAD  SwiTCHGEAR.     Electrical  Review,  London,  July  24,  1908. 
METER  AND  RELAY  CONNECTIONS.     H.  W.  Brown.     Electric  Journal,  May,  1908. 
SWITCHING  APPARATUS  AND  ITS  PRACTICAL  OPERATION  IN  LARGE  HYDRO-ELECTRIC  STATION.     Frank 

E.  Conrad.     Electrical  World,  July  25,  1908. 
OPERATION  OF  LARGE  HYDRO-ELECTRIC  STATION  SWITCHING  APPARATUS.     F.  E.  Conrad.    Electrical 

World,   May  30,    1908. 
SOME  FEATURES  OF  EUROPEAN  HIGH-TENSION  PRACTICE.     Frank  Koester.    Electrical  Age,  December, 

1008. 
SWITCHBOARD  PRACTICE  FOR  VOLTAGES  OF  60,000  AND  UPWARD.    Stephen  Q.  Hayes.    Pro.  Am. 

Inst.  E.  E.,  June,  1907. 


\ 


PART    II. 

THE  TRANSMISSION   OF   HIGH   TENSION 
ELECTRICAL   CURRENT. 


PART    II. 

THE   TRANSMISSION    OF   HIGH    TENSION    ELECTRICAL    CURRENT. 


CHAPTER   VIII. 
ELECTRICAL   TRANSMISSION. 

A  TRANSMISSION  line  should  run  at  low  levels  and  near  highways,  to  facilitate 
erection,  inspection  and  repair;  it  must  further  be  borne  in  mind  that  the  line  must  be 
as  straight  and  short  as  possible,  to  minimize  first  cost,  maintenance,  line  loss,  and 
the  expenditure  for  securing  the  right  of  way.  Where  the  line  runs  through  moun- 
tainous countries,  high  peaks  must  be  avoided,  because  the  temperature  range 
between  peak  and  valley  is  great  and  atmospheric  electrical  discharges  are  frequent. 
It  is  therefore  better  policy  to  detour  the  line  than  be  troubled  with  atmospheric 
discharges. 

For  high-tension  lines,  two  separate  circuits  must  be  run  either  on  a  common  or 
two  separate  towers,  so  that  one  is  always  in  reserve.  Such  lines  must  be  divided 
up  into  sections,  provided  with  section  switches  and  by-pass  connections,  so  that  a 
continuity  of  service  is  assured.  The  sections  may  be  about  20  miles  long,  and  at 
the  end  of  each  section  must  be  a  repair  shop  and  accommodations  for  the  patrolman, 
whose  duty  is  to  inspect  the  section  once  or  twice  a  day.  All  poles  and  towers  must 
be  properly  numbered  to  facilitate  the  location  of  trouble. 

Telephone  connections  must  be  established  at  the  patrolman's  quarters  and  at 
frequent  intervals.  For  further  convenience,  portable  telephones  may  be  used. 
The  telephone  line,  in  duplicate,  is  best  run  on  separate  poles,  and  is  also  used  for 
telegraph  purposes.  These  lines  must  be  for  the  exclusive  use  of  the  transmission 
company. 

TRANSMISSION    CONDUCTORS. 

Strength  of  Conductors.  Aerial  lines  transmit  the  electrical  energy  from  hydraulic 
plants  to  the  center  of  distribution.  The  material  used  for  conductors  is  copper, 
hard  or  soft  drawn,  aluminum  and  steel;  all  three  are  used  in  cable  form,  while 
copper  is  sometimes  used  as  solid  conductor. 

For  transmission  purposes,  hard  drawn  copper  is  almost  always  used,  as  it  has  an 
ultimate  tensile  strength  of  60,000  pounds  per  square  inch,  while  that  of  soft  drawn 
copper  is  only  30,000  pounds.  The  resistance  of  the  former  is  5  per  cent  greater 
than  that  of  the  latter.  Aluminum  has  a  tensile  strength  of  about  28,000  pounds; 
while  steel  varies  greatly,  it  averages  100,000  pounds. 

215 


216  HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 

Elasticity  of  Conductors.   The  elasticity  of  a  cable  is  much  greater  than  that  of 
a  sojid  wire,  therefore  cables  are  preferable  for  long-span  transmission  lines. 

TABLE    I. —  MODULUS    OF    ELASTICITY. 


Copper  wire,  hard  drawn  

Copper,  hard  drawn  cable  strand  

1  6  300  ooo 

Aluminum,  hard  drawn  

Steel  wire  

TABLE    II.  —  COEFFICIENT    OF    EXPANSION    PER    DEGREE 
FAHRENHEIT. 


Copper  .  . 

o  0000006 

Aluminum  

Steel  

From  the  tables  it  will  be  seen  that  steel  cables  compare  very  favorably  for  long 
spans,  but  the  disadvantage  is  the  low  conductivity,  being  only  12,  while  that  of 
copper  is  100. 

Cables  as  Conductors.  The  strands  in  a  cable  must  be  continuous,  to  give  it 
uniform  strength  and  conducting  area.  The  lengths  of  cable  obtainable  are  longer 
than  those  of  a  solid  conductor,  for  the  reason  that  a  cable  is  made  up  of  a  number 
of  small  strands,  each  of  which  is  made  from  the  same-sized  ingot  as  a  larger  con- 
ductor. The  weights  of  cables  are  calculated  about  one  per  cent  heavier  than  a  solid 
wire  of  the  same  circular  millage,  while  the  resistance  is  calculated  for  a  solid  con- 
ductor. The  number  («)  of  strands  in  a  cable  of  given  circular  millage  (C.M.), 
composed  of  wires  of  diameter  (d),  is  found  by  the  following  formula: 

C.M.  =  d2  X  n. 
C.M. 


The  diameter  of  a  cable  is  found  by  multiplying  the  diameter  of  one  wire  by  the 
factors  given  in  Table  III,  according  to  the  number  of  strands  composing  the  cable. 
Another  convenient  table  on  this  subject  is  found  in  the  appendix. 


TABLE    III. —  STRAND    FACTOR. 


Number  of   strands 

Factor. 

3 

2.25 

7 

3.00 

12 

4-25 

19 
27 

5.00 
6.25 

ELECTRICAL  TRANSMISSION.  217 

Spacing  of  Conductors.  The  spacing  of  conductors  depends  on  the  voltage  and 
on  the  length  of  the  spans,  and  varies  from  24  to  96  inches.  The  increase  in  spacing 
increases  the  inductive  drop,  and  also  the  line  loss.  There  are  no  fixed  rules  estab- 
lished for  the  spacing  of  conductors.  The  following  are  approximate  distances:  for 
voltages  from  5000  to  10,000,  24  to  36  inches;  for  10,000  to  30,000,  36  to  60  inches; 
for  30,000  to  60,000,  60  to  84  inches;  for  60,000  to  100,000  and  higher,  from  84  to 
96  inches. 

Characteristics  of  Conductors.  Comparing  the  specific  gravities  of  aluminum  and 
copper,  the  latter  is  about  3.3  times  greater  than  the  former,  so  that  for  cables  of 
equal  length  and  resistance,  the  copper  cable  is  twice  as  heavy  as  the  aluminum. 
As  the  tensile  strength  is  only  about  28,000  pounds  per  square  inch,  aluminum  wires 
must  be  used  only  in  the  form  of  a  cable.  For  equivalent  conditions,  the  diameter 
of  an  aluminum  cable  is  1.28  times  that  of  copper,  while  the  cross-sectional  area  is 
about  1.65  times  larger,  because  the  conductivity  of  aluminum  is  only  63  per  cent 
that  of  copper.  Cables  present  a  larger  surface  to  the  wind,  and  also,  for  the  forma- 
tion of  ice.  The  advantages  gained  in  the  use  of  aluminum  are,  cheaper  than  copper 
and  light  weight,  which  in  turn  reduces  the  cost  of  pole  line  construction.  Owing 
to  the  high  coefficient  of  expansion,  aluminum  wires  must  be  strung  either  in  the 
spring  or  fall,  preferably  the  latter.  Heretofore,  much  difficulty  was  experienced 
in  splicing  cables  of  aluminum;  this  has  been  overcome  in  recent  practice. 

According  to  the  laws  of  transformation  of  alternating  currents,  the  higher  the 
voltage,  the  smaller  the  current  for  a  given  amount  of  power,  and  vice  versa.  So 
far  as  the  transmission  line  itself  is  concerned,  the  highest  voltage  which  can  commer- 
cially be  produced,  is  the  best  voltage.  A  small  current  on  the  line  means  that  the 
size  of  wire  can  be  reduced  until  the  mechanical  strength  of  the  wire  predominates. 
The  use  of  high  voltages  reduces  the  line  drop,  losses  in  transmission,  and  gives  better 
regulation  than  low  voltages. 

Size  of  Conductors.  The  essential  factors  necessary  for  calculating  the  size  of 
line  conductors  are:  the  load  to  be  transmitted,  the  voltage  desired  at  the  receiving 
end,  the  permissible  loss  of  energy  in  transmission,  the  frequency,  spacing  of  the 
wires  on  the  cross-arms,  length  of  transmission  line. 

The  size  of  conductors  is,  for  standard  sizes,  usually  designated  by  a  number; 
for  sizes  larger,  they  are  designated  by  their  cross-sectional  area  in  circular  mils. 
The  largest  standard  size  is  oooo  and  is  0.46  of  an  inch  in  diameter. 

The  circular  mil  is  the  thousandth  part  of  an  inch,  and  is  chosen  as  the  unit  of 
measurement  for  electrical  conductors.  Thus  the  diameter  of  a  one-inch  cable  is 
1000  mils,  and  its  area  is  a  million  circular  mils  or  (iooo)2  circular  mils. 


218  HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 

In  calculating  the  size  of  transmission  conductors  it  is  poor  policy  to  use  a  larger 
conductor  than  is  absolutely  necessary.  This  fact  is  well  illustrated  in  a  law 
developed  by  Lord  Kelvin,  and  known  by  that  name.  The  usual  way  of  stating 
it  is:  "  The  most  economical  area  of  conductor  will  be  that  for  which  the  annual 
interest  on  the  capital  outlay  equals  the  annual  cost  of  the  energy  wasted."  A 
more  precise  statement  of  the  same  thing  is  given  by  Gisbert  Kapp,1  "  The  most 
economical  area  of  conductor  is  that  for  which  the  annual  cost  of  the  energy  wasted 
is  equal  to  the  interest  on  that  portion  of  the  capital  outlay  which  can  be  considered 
to  be  proportional  to  the  weight  of  the  metal  used." 

Direct  Current  Conductors.  For  calculating  the  size  of  conductors  for  direct 
current  distribution  the  following  formulas  suffice: 

_K.W.  X  looo 
E 

2  X  D  XI  X  ii  .. 

=  size  of  conductor  in  circular  mils. 

E  X  p 

K.W.  =  load  in  kilowatts. 

/  =  current. 

E  =  voltage. 

D  =  distance  one  way  in  feet. 

ii  =  resistance  of  copper  per  mil-foot. 

p  =  percentage  drop  in  voltage. 

Direct  Current  Problem.  For  example,  it  is  desired  to  transmit  500  K.W.  at 
500  volts  for  a  distance  of  two  miles  with  a  line  drop  of  10  per  cent. 

2  miles  =  5280  X  2  =  10,560  ft. 

500  X  1000 

Then  /  =  -  =  1000  amp. 

500 

2  X  10,560  X  looo  X  ii 

C.M.  =  -  =  4,646,400. 

500  X  o.io 

Upon  consulting  the  wire  tables  it  will  be  seen  that  this  is  not  of  standard  size, 
in  fact  it  is  a  little  less  than  22  wires  of  No.  oooo,  the  largest  standard  size. 

Suppose  22  wires  were  used.  The  resistance  of  the  whole  circuit  is  one  twenty- 
second  of  one  circuit  of  No.  oooo.  The  resistance  of  No.  oooo  is  about  0.05  ohm 
per  1000  feet.  The  resistance  for  the  whole  is  2  X  10.56  X  .05  -*•  22  =  0.048  ohm. 

To  check  up  results  on  this  assumption, 

Voltage  drop  =  0.048  X  1000  =  48  volts. 

-  X  100  =  9.6  per  cent,  line  drop. 
500 

(icoo)2  X  0.048  -5-  1000  =  48  K.W.,  line  loss. 

48  -H  500  X  100  =  9.6  per  cent,  energy  loss  in  transmission. 

1  Economical  Conductor  Section,  by  Frank  G.  Baum.     Electrical  World,  May  25,  1907. 


ELECTRICAL  TRANSMISSION. 

If  in  the  above  calculations  the  voltage  be  doubled,  the  size  of  the  wire  will  be 
only  one-quarter  as  great;  that  is,  the  amount  of  copper  varies  inversely  as  the  squt 
of  the  voltage. 

Alternating  Current  Conductor.  In  the  calculations  of  alternating  currents  new 
factors  have  to  be  taken  into  consideration,  and  their  value  depends  upon  the  fre- 
quency and  the  distance  the  wires  are  apart,  etc.  In  direct  current  transmission  the 
losses  can  be  calculated  either  E  X  I  or  PR,  but  in  alternating  current  only  PR 
gives  the  real  loss;  E  X  I  gives  the  apparent  loss. 

Alternating  Current  Problem.  For  single  phase  transmission  the  following  exam- 
ple gives  approximate  results.  Suppose  a  load  1000  K.W.  is  to  be  received  at  a 
distance  of  ten  miles  at  10,000  volts,  frequency  25  cycles,  power  factor  0.85,  line 
loss  10  per  cent,  wires  spaced  36  inches  apart. 

1000  K.W.  =  actual  energy. 
1000  -4-  0.85  =  1176.4  K.W.,  apparent  energy. 
1176.4  X  1000  -T-  10,000  =  117.64  amperes. 
PR  =  (117.64)^  =  line  loss. 

Also  £        1000  K.W.  X  10  per  cent  =  ioo  K.W.,  line  loss. 

Then  (n 7.64) 2  X  R  =  ioo  X  1000. 

ioo  X  1000 

R  =  •  =  7.23  ohms  (total). 

(ii7.64)2 

7.23  X  1000 

Resistance  per  1000  feet  =  -  — -  =  0.0684  ohm. 

2  X  10  X  5280 

This  corresponds  nearly  to  a  No.  oo  wire,  which  has  a  resistance  of  0.076  ohms 
per  1000  feet. 

The  resistance  of  the  circuit  with  No.  oo  is 

5.280  X  2  X  10  X  0.076  =  8.02  ohms. 

117.6  X  8.02  =  941  volts;  resistance  volts. 

To  calculate  the  drop  due  to  reactance,  recourse  to  Table  VII  is  necessary.  It 
represents  the  reactance  volts  per  ampere  per  1000  feet  of  line  (2000  feet  of  wire) 
at  60  cycles.  For  distances  not  given  in  the  tables  interpolations  are  made  directly. 
From  the  table  the  constant  for  No.  oo  placed  at  36  inches  is  0.254.  This  is  the 
drop  per  ampere  at  60  cycles.  As  this  value  varies  directly  with  the  frequency,  for 
25  cycles  the  reactance  volts  are 

105.6  (thousands  of  feet)  X  117.6  X  0.254  X  —  =  1314- 

60 

The  line  drop  is  not  current  X  resistance,  but 


\/(94i)2  +  (1314)*  =  1597- 

1597  H-  (10,000  +  1597)  X  ioo  =  13.77  Per  cent>  drop  in  generator  station  voltage. 

(117. 6)2  X  8.02  -T-  1000  =  17.24  K.W.,  line  loss. 
17.24  -5-  (1000  +  17.24)  X  ioo  =  16.9  per  cent,  loss  of  energy  in  transmission. 


22O 


HYDROELECTRIC  DEVELOPMENTS  AND  ENGINEERING. 


TABLE    IV.  —  COMPARISON    OF    WIRE    GAUGES. 


No. 

A.  W.  G. 
Brown  &  Sharpe. 
(B.  &  S.  G.) 

Stubs. 
Birmingham. 
(B.  W.  G.) 

(N.  B.  S.) 
English  Standard. 
(S.  W.  G.) 

A.  S.  &  W.  Co. 

Washburn  &  M. 
Roebling's. 

Diam. 
Mils. 

Cir. 
Mils. 

Diam. 
Mils. 

Cir. 

Mils. 

Diam. 
Mils. 

Cir. 
Mils. 

Diam. 

Mils. 

Cir. 

Mils. 

oooooo  

580.  oo 
516.50 
460.00 
409  .  64 

364.80 
324.86 
289.30 
257-63 

229.42 
204.31 
181.94 
162.02 

144.28 
128.49 

H4-43 
101  .  89 

90.742 
80.808 
71.964 

64.084 

57.068 

50.820 

45-257 
40.303 

35-890 
31.961 
28.462 
25-347 

22.571 

20.  IOO 

336,400 
266,772 
211,600 
167,805 

133.079 
105,534 
83,694 

66,373 

52,633 
4i,742 
33,i°2 
26,250 

20,817 
16,509 

i3>094 
10,381 

8,234.  i 
6,529.9 

5,178-4 
4,106.8 

3.256-8 
2,582.7 
2,048.2 
1,624.3 

1,288.1 
1,021.5 
810.08 
642.47 

509-45 
404.01 

464 
432 

400 

372 

348 
324 
300 
276 

252 
232 

212 
192 

I76 

160 
144 
128 

116 
104 
92 

80 

72 
64 
56 
48 

40 
36 

11 
24 

22 

215,296 
186,624 
1  60,000 
138,384 

121,104 
104,976 
90,000 
76,176 

63,504 
53,824 
44,944 
36,864 

30,976 
25,600 
20,736 
16,384 

13.456 
10,816 
8,464 
6,400 

5.184 
4,096 
3.136 
2,304 

i,  600 
1,296 
1,024 
784 

576 
484 

460 
43° 
394 
363 

33i 

307 
283 
263 

244 
225 
207 
192 

177 
162 
148 

135 

121 

106 

92 

80 

72 
63 
54 
48 

4i 
35 
32 
29 

26 
23 

211,600 
184,900 
154,764 
131,406 

109,561 

94,249 
80,089 
69,169 

59,536 
50,625 
42,849 
36,864 

31.329 
26,244 

21,904 
18,225 

14,520 
11,130 
8,464 
6,400 

5.184 
3.969 
2,916 
2,256 

i,  68  1 
1.225 
1,024 
818 

666 
529 

1 

ooooo  

oooo  

454 
425 

380 
340 
300 
284 

259 
238 
220 
203 

180 

165 
148 

134 

1  20 
109 
95 
83 

72 
65 
58 
49 

42 
35 
32 

28 

25 

22 

206,116 
180,625 

144,400 
115,600 
90,000 
80,656 

67,081 
56,644 
48,400 
41,209 

32,400 
27,225 
21,904 
17,956 

14,400 
11,881 
9,025 
6,889 

5.184 
4,225 

3,364 
2,401 

1,764 
1,225 
1,024 
784 

625 
484 

ooo  

oo  

o  

I  

2  

A.  . 

e.  . 

6  

7  

8  

10  ; 

ii  

12  

H  •  • 

14  

1C  .  . 

16  

17  .  . 

18  

10.  . 

20  

21  

22  

27  .  . 

24  

N.  B.  —  S.  W.  G.  has  No.  ooooooo;  diameter,  500  mils;  area,  350,000  cir.  mils. 


ELECTRICAL  TRANSMISSION. 


221 


TABLE  V.  — SOLID  COPPER  WIRE. 

BARE  AND  INSULATED. 


Diam.  Mils. 

Weight,  pounds. 

Resistance. 

Carrying  ca- 
pacity.    Amp. 

No. 

Area. 

T.  B. 

Int.  Ohms,  20°  C. 
(68°  F.)-Matt.  Std. 

B.  &S. 

T.  B. 

Cir.  Mils. 

Bare. 

Weatherproof. 

i6°F. 
rise, 

32°F. 

Bare. 

Weather 

con- 

r s  , 

proof. 

1000'. 

Mile. 

1000'. 

Mile. 

1000'. 

Mile. 

cealed. 

open. 

oooo 

460 

780 

211,600 

640.5 

3.38i 

754 

3,98o 

.  04893 

-2583 

2IO 

312 

000 

409.  6 

700 

167,805 

508.0 

2,682 

614 

3,240 

.06170 

•3258 

177 

262 

00 

364.8 

635 

I33.079 

402.8 

2,127 

486 

2,570 

.07780 

.4108 

ISO 

22O 

o 

324.9 

59° 

105.534 

3I9-5 

1,687 

388 

2,050 

.09811 

.5180 

127 

I85 

I 

289.3 

55° 

83,694 

253-3 

i,337 

312 

1,650 

.12370 

•6531 

107 

156 

2 

257.6 

5i5 

66,373 

200.  9 

1,062 

254 

1,340 

.1560 

.8237 

90 

131 

3 

229.4 

45° 

52.633 

159-3 

841.1 

201 

i,  060 

.1967 

1.0386 

76 

110 

4 

204.3 

43° 

4i,742 

126.4 

667.4 

I63 

860 

.  2480 

1.3094 

65 

92 

5 

181.9 

400 

33,102 

100.  2 

529.0 

134 

710 

.3128 

1.6516 

54 

77 

6 

162.0 

360 

26,250 

79.46 

4I9-5 

112 

59° 

•3944 

2.0824 

46 

65 

7 

J44-3 

335 

20,817 

63.02 

332-7 

89 

47° 

•4973 

2.6257 

39 

55 

8 

128.5 

280 

16,509 

49.98 

263.9 

73-8 

39° 

.6271 

3-3III 

33 

46 

9 

114.4 

255 

i3,094 

39-63 

209.  2 

60.6 

320 

.7908 

4-1754 

28 

38 

10 

101.9 

220 

10,381 

31-43 

166.0 

50.2 

265 

.9972 

5-2652 

24 

32 

ii 

90.74 

205 

8,234 

24-93 

131.6 

42.  6 

225 

1-257 

6.  6370 

20 

27 

12 

80.  81 

I85 

6,530 

19.77 

104.4 

35-o 

185 

1.586 

8-374 

17 

23 

13 

71.96 

170 

5,i78 

15-68 

82.79 

30-3 

160 

1.999 

10.  560 

14 

19 

14 

64.08 

160 

4,107 

12.43 

65-63 

25-9 

137 

2.521 

^•sn 

12 

16 

15 

S7-°7 

*55 

3,257 

9.858 

52-05 

22.  7 

I2O 

3-179 

16.785 

9 

12 

16 

50.82 

15° 

2,583 

7.M 

41.28 

19.9 

105 

4.  009 

21.  i.  68 

6 

8 

i? 

45.26 

147 

2,048 

6.  200 

32-74 

18.0 

95 

5-°55 

26.  690 

4-5 

6-5 

18 

40.30 

i45 

1,624 

4.917 

25.96 

16.  i 

85 

6-374 

33-655 

3 

5 

19 

35.89 

140 

1,288 

3-899 

20.59 

14.2 

75 

8.038 

42.440 

2-3 

4 

20 

31.96 

i35 

1,022 

3.092 

16.33 

12.3 

65 

10.  14 

53-540 

i-5 

3 

A.I.E.E. 

s.u.c.c. 

A.  I.  E.  E. 

Average.1 

A.  I.  E.  E. 

Nat.  Elec.  Code. 

1  Std.  Und.  Cable  Co.,  J.  A.  Roebling's  Co.,  Amer.  Elec.  Works,  Gen.  Elec.  Co.,  Amer.  St.  &  W.  Co.,  Hazard 
Mfg.  Co. 


222 


HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 


TABLE    VI. —  STRANDED    COPPER    WIRE. 
BARE   AND  INSULATED. 


Diam.  Mils. 

Weight,  pounds. 

Resistance. 

Carrying 

Int.  Ohms,  20°  C. 

capacity. 

No.  and 

(68°  F.)  Matt.  Std. 

Amperes. 

Diam.  of 

T.  B. 

Strands 

Area. 

Bare. 

Weatherproof. 

or  Size 

T.  B. 

Cir.  Mils. 

Bare. 

Weather- 

16   F. 

O   p 

B.  &  S. 

proof. 

1000'. 

Mile. 

rise, 

rise, 

1000'. 

Mile. 

i  ooo'. 

Mile. 

con- 

cealed. 

open. 

9i/.  128 

1,408 

1.875 

1.500,000 

4,575 

24,156 

5,335 

28,169 

.  006902 

.03644 

850 

1,360 

9i/.  117 

1,287 

i,775 

1,250,000 

3,813 

20,132 

4,45° 

23,496 

.008282 

•04373 

750 

1,185 

6i/.  128 

,I52 

1,6.35 

t  ,000,000 

3.050 

16,104 

3,610 

19,061 

•010353 

.05466 

650 

I,  OOO 

6i/.  125 

,125 

i,  600 

950,000 

2,898 

I5>299 

3,450 

18,216 

.  010900 

•05755 

625 

960 

6l/.  121 

,092 

1.525 

900,000 

2,745 

14,494 

3,268 

17,255 

.01150 

.06072 

600 

920 

6i/.  118 

,062 

1,500 

850,000 

2,593 

13,688 

3,083 

16,278 

.01218 

.06431 

575 

880 

6i/.  115 

,035 

1,475 

800,000 

2,440 

12,883 

2,905 

15,338 

.01294 

.  06832 

550 

840 

6i/.  in 

999 

1,425 

750,000 

2,288 

12,078 

2,730 

14,415 

.01380 

.07286 

525 

Soo 

6i/.  107 

963 

1,405 

700,000 

2,i35 

",273 

2,569 

13.565 

.01479 

.  07809 

5°° 

760 

6r/.  103 

927 

i,375 

650,000 

1,983 

10,468 

2,393 

12,635 

•01593 

.08411 

475 

720 

6i/.o99 

891 

600,000 

1,830 

9,662 

2,215 

11,695 

.01725 

.09108 

45° 

680 

617.095 

855 

1,300 

550,000 

1,678 

8,857 

2,040 

10,771 

.01882 

•09937 

420 

635 

6i/.ogi 

819 

1,250 

500,000 

1,525 

8,052 

1,870 

9,875 

.02070 

•  10930 

390 

590 

37/.  110 

770 

1,200 

450,000 

1,373 

7,247 

1,694 

8,945 

.  02300 

.12144 

360 

545 

37/-I04 

728 

I,19O 

400,000 

'i,  220 

6,442 

1,529 

8,075 

.02588 

•  13664 

33° 

500 

37/-097 

679 

1,125 

350,000 

i,  068 

5,636 

1,320 

6,970 

.02958 

.15618 

300 

45C 

377.090 

630 

955 

300,000 

9i5 

4,831 

i,i33 

5,982 

•03451 

.18221 

270 

400 

37/-o83 

59° 

920 

250,000 

762 

4,026 

940 

4,963 

.04141 

.21864 

235 

35C 

oooo  B  &S 

530 

805 

211,600 

641 

3,381 

779 

4,115 

•  04893 

•2583 

210 

312 

ooo    " 

47° 

75o 

167,805 

508 

2,682 

650 

3>432 

.06170 

•3258 

177 

262 

00       " 

420 

660 

133,079 

403 

2,127 

527 

2,785 

.07780 

.4108 

150 

220 

o     " 

375 

615 

105,534 

320 

1,687 

43° 

2,270 

.09811 

.5180 

127 

185 

I   " 

330 

575 

83,694 

253 

i>337 

326 

1,722 

.12370 

•6531 

.    1C? 

156 

2       " 

291 

535    ' 

66,373 

2OI 

1,062 

270 

1,426 

..  15600 

.8237 

90 

131 

3     " 

261 

475 

52,633 

159 

841 

218 

1,15° 

.  19670 

1.0386 

76 

no 

4 

231 

4i,742 

126 

667 

176 

93° 

.  2480 

I  .  3094 

65 

92 

Haz.  M.C. 

J.AR 

Haz.  M.C. 

A.I.E.E. 

J.  A.  Roebling's 

Haz.  Mfg.  Co. 

A.  I   E.  E. 

Nat  Elec.  Code 

ELECTRICAL   TRANSMISSION. 

TABLE    VII.  —  REACTANCE    VOLTS. 


223 


Distance  apart  of  conductors  in  inches. 

Size  of 

Conductor. 

i2-inch. 

1  8-  inch. 

a  4-  inch. 

30-  inch. 

36-inch. 

48-inch. 

96-inch 

OOOO 

•193 

.  212 

.225 

•235 

.244 

•251 

.283 

ooo 

.199 

.217 

•  230 

.241 

.249 

•255 

.287 

oo 

.  204 

.  222 

•236 

.246 

•254 

.  262 

.294 

0 

.  209 

.228 

.241 

•251 

•259 

.  267 

.299 

I 

.214 

•233 

.  246 

.256 

•  265 

•273 

•3°5 

2 

.220 

.238 

.252 

.  262 

.270 

•277 

•309 

3 

.225 

•244 

•257 

.  267 

•275 

.282 

•3M 

4 

.230 

.249 

.  262 

.272 

.281 

.294 

.326 

5 

.236 

•254 

.268 

.278 

.286 

.299 

•331 

6 

.241 

.  260 

.272 

.283 

.  291 

•3°5 

•337 

7 

.246 

.265 

.278 

.288 

.  296 

.310 

•  342 

8 

.252 

.  270 

.284 

•293 

.302 

•3i5 

•347 

TABLE    VIII. —  WEIGHT    AND    STRENGTH    OF    ELECTRICAL    WIRES. 


Weight.  —  Pounds  per  1000  feet  (bare). 

Breaking  weight.  —  Pounds. 

No. 

B.  &S. 

Copper 

&  Phono- 

Alum- 

Wrought 

Copper, 

Copper, 

Phono- 

Alum- 

Charcoal 

Crucible 

Elec. 

inum. 

Iron. 

Steel. 

Hard. 

Soft. 

Electric. 

inum. 

Iron, 

Steel. 

Bright 

Ordinary 

0000 

640.5 

192.86 

553-97 

565-50 

8,310 

5,650 

11,460 

4,15° 

13,000 

16,250 

ooo 

508.0 

I52-94 

439-33 

448.45 

6,580 

4,480 

9,140 

3,290 

10,400 

13,000 

oo 

402.  8 

121.28 

348.40 

355-65 

5,226 

3,553 

7,400 

2,620 

8,350 

10,430 

o 

3I9-5 

96.18 

276.30 

282.02 

4,558 

2,818 

6,300 

2,070 

6,650 

8,300 

I 

253-3 

76.29 

219.  ii 

223.  68 

3,746 

2,234 

5,250 

1,640 

5,45° 

6,810 

2 

200.9 

60.50 

I73-78 

I77-38 

3-129 

1,772 

4,180 

1,300 

4,3°o 

5,370 

3 

159-3 

47-97 

137.80 

140.  67 

2,480 

1,405 

3>36o 

1,030 

3,550 

4,43° 

4 

126.4 

38-05 

109.  28 

ni-57 

1,967 

1,114 

2,700 

819 

2,850 

3,56o 

5 

100.  2 

30.17 

86.68 

88.46 

i,559 

883 

2,080 

650 

2,300 

2,875 

6 

79-5 

23-93 

68.73 

70.15 

1,237 

700 

1  ,680 

515 

1,850 

2,310 

7 

63.0 

18.98 

54-43 

55-56 

980 

555 

1,350 

408 

1,500 

1-875 

8 

50.0 

I5-05 

43-23 

44.12 

778 

440 

I.07S 

324 

1,200 

1,500 

9 

39-6 

"•93 

34.28 

34-99 

617 

349 

850 

255 

970 

1,210 

10 

3i-4 

9.46 

27.18 

27.74 

489 

277 

68S 

204 

765 

955 

ii 

24.9 

7-5i 

21.56 

22.  OI 

388 

219 

545 

162 

610 

762 

12 

19.8 

5-95 

17.  10 

17.46 

3°7 

174 

420 

128 

49° 

612 

13 

iS-7 

4-72 

I3-56 

I3.84 

245 

138 

340 

103 

395 

493 

14 

12.4 

3-74 

10-75 

10.98 

*93 

109 

270 

84 

3i5 

394 

15 

9-9 

2-97 

8-53 

8.70 

153 

87 

220 

67 

255 

319 

16 

7.8 

2-35 

6.76 

6.90 

133 

69 

1  80 

52 

205 

256 

17 

6.2 

1.87 

5-36 

5-47 

97 

55 

i35 

42 

170 

212 

18 

4-9 

1.48 

4-25 

4-34 

77 

43 

107 

34 

*35 

169 

*9 

3-9 

1.17 

3-37 

3-44 

61 

34 

86 

27 

no 

137 

20 

3-i 

•93 

2.  67 

2-73 

48 

27 

70 

21 

90 

112 

Weight.  —  Pounds  per  cubic  inch. 

Tensile  strength.  —  Pounds  per  square  inch. 

50,000 

69,000 

25,000 

78,000 

97,000 

.322 

.0967 

.278 

.284 

6o,000 

34,000 

85,000 

39,000 

112,000 

140,000 

Authority 

B.  B.  Co. 

Pittsburgh  Reduction  Co. 

Bridgeport  Brass  Co. 

P.  R.  Co. 

Trenton  Iron  Co. 

224  HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 


TABLE    IX. —  AMERICAN    AND    ENGLISH    STANDARD    COPPER    CABLE. 

STRANDED,    BARE. 


American. 
B.  &S. 

English. 
No.  and 
Diameter 
of  Single 
Strands. 

Diam.  Cable. 

Area. 

Weight. 

Resistance.  —  Int.  Ohms. 

Inch. 

mm. 

Sq.  In 

Sq.  mm. 

Cir.  Mil. 

Lb. 

loooft 

Kilog. 
Kilom 

Matt.  Std.-2o°C. 

60°  F. 

IOOO 

Yd. 

1000  Ft. 

Kilom. 

4 
3 

3 

I 

O 
00 

coo 
oooo 

250,000  cm. 
300,000    " 

400,000    " 
500,000    " 

600,000    " 
700,000    " 
800,000    " 

i  ,000,000  '  ' 

7/.o68 
7/-095 

.  204 

•23i 
.  261 
.285 
.291 
•33° 
.360 

•375 
.410 
.420 
.460 
.470 
•5°5 
•53° 
•574 
•59° 
.630 
.707 
.728 
.819 
.828 
.891 
.909 

•963 
.990 

i-°35 
1.078 
1.144 

I.  I<C2 

5.18 

5-8? 
6.63 
7.24 

7  39 
8.38 
9.  14 

9-52 
10.  41 
10.  67 
11.68 
11.94 
12.83 
13.46 

14-59 
14.99 
1  6.  oo 
17.96 
18.50 
20.80 
21.03 
22.63 
23.10 
24.48 

25-15 
26.30 
27.40 
29.06 
29.25 
C 

.025 

.0328 
.041; 
.050 
.0521 
.0657 

-075 
.0829 
.  IOO 

•  I045 
•125 
.132 
.150 
.166 
.200 
.  196 
•  236 
.300 
•3H 

•393 
.400 

•471 
.500 

•55° 
.600 
.628 
.700 
.800 

•785 
D-B-C 

1  6.  13 
21.15 
26.65 
32  -3° 
33-65 
42.40 
48.  40 
53.48 
64.52 
67.50 
,   81.50 
85.00 

98.  20 
107.  2 
129.0 
126.7 
152.0 
194.0 
202.  7 
253-4 
258.5 
304.0 

323-0 

354-7 
388.0 
405  4 
452-0 

451-7 
506.7 
C 

32,400 
41,742 
52,633 
63,150 

66,373 
83,694 
98,500 
105,534 
127,800 

133,079 
160,800 
167,805 
193,800 
211,600 
248,500 
250,000 
300,000 
377,200 
400,000 
500,000 
516,000 
600,000 
622,000 
700,000 
738,000 
800,000 
874,000 
984,000 

1,000,000 

A-C 

IOO 
126 
159 

J93 

2OI 
253 
3°4 
320 

394 
403 
496 

513 
594 
645 
768 
762 

915 
1,165 
1,220 

I>525 
i,59i 
1,830 
1,921 

2,i35 
2,279 

2,440 
2,698 
3-038 

3-05° 
R-B 

149 
189 
238 
287 
3°2 
380 
453 
479 
586 
605 
738 
766 
886 
960 
1,144 

i,1  35 
1,362 

i,735 
1,815 
2,268 

2.372 

2,725 
2,860 
3,180 
3,390 
3-630 
4,015 
4,524 
4-540 
C 

.320 

.  2480 
.1967 
.  1640 
.1560 
•1237 
.1051 
.09811 
.08100 
.07780 
.  06440 
.06170 
•05340 
•  04893 
.04170 
.04141 

•03451 
.02748 
.02588 
.02070 
.  02008 
.01725 
.01666 

•01479 
.01403 
.01294 
.01185 
.01052 
•01035 
A 

1.050 
.814 
•6452 
•5380 

•5JI9 
.4058 

•  3446 
.3220 
•2655 
•2552 

.  2112 

.  2O24 

•1752 
.  1606 
.1367 
.1360 
.1132 
.O90I 
.0849 
.0679 
.0662 
.0566 
.05468 
.04850 
.04602 
.04250 
.  03888 
•03450 
.03396 

C 

.962 

•493 

197.072 
197.082 
197.092 
i9/.  101 

•317 
.244 
.194 

.161 

37/.o82 

•125 

37/-ioi 

.0827 

617.092 

.0605 

6i/.  101 
6i/.  no 

917.098 
9i/.  104 

.0502 

.0423 

•0357 
•°W 

B 

R-C 

B 

AUTHORITIES.  —  A — Amer.  Inst.  Elec.  Eng.;  B — Standard  of  Cable  Makers'  Ass.,  Feb.  5,  1903,  England; 
C — Calculated  from  Strand  or  by  Conversion;  R — J.  A.  Roebling's  Sons  Co.;  D — Heavy  figures  denote  nominal  English 
sizes,  but  check  only  approximately  with  other  quantities. 


ELECTRICAL   CURRENT. 

TABLE    X.  — AMERICAN    AND    ENGLISH    SOLID    COPPER    WIRE. 

BARE,   WITH   ENGLISH  AND  METRIC  MEASURES. 


225 


American  . 
B.  &S. 

English. 
S.  W.  G. 

Diameter. 

Area. 

Weight. 

Resistance-  20°  C. 
Int.  Ohms.  (68°F.) 
Matthiessen's  St'd. 

Inch. 

mm. 

Sq.  In. 

Sq.  mm. 

Cir.  Mils. 

Pounds. 
1000'. 

Kilog. 
Kilom. 

1000'. 

Kilom. 

7-0 
6-0 

.5000 
.4640 
.4600 
.4320 
.  4096 

.4000 
.3720 
.3648 
.3480 
•3249 

.3240 

.3000 
.2893 
.  2760 
.2576 

•  252O 
.2320 
.2294 
.  2120 
.2043 

.  I92O 
.  1819 
.  1760 
.  l62O 
.  l6oO 

•1443 
.1285 
.  1160 

•  1  1'44 
.  1040 

.  1019 
.0920 
.0907 
.0808 
.0720 

.0641 

•057i 
.0560 
.0508 
.0480 

•°453 
.0403 

•°359 
.0320 
.0285 

.  0280 
•  0254 
.0240 
.0226 
.0201 

I  2  .  700 
11.785 
11.683 
10.972 
10.404 

10.  160 
9.448 
9.  266 
8.839 
8.251 

8.  229 
7.  620 
7-348 
7.010 
6-544 

6.401 

5-893 
5.827 

5.385 
5.190 

4-877 
4.621 
4.470 

4-115 
4.064 

3-665 
3-263 
2.947 

2.  906 
2.641 

2.588 

2-337 
2-305 
2.052 
1.828 

1.628 
1.449 
1.422 
i.  291 
i.  219 

1.150 
1.024 
.9116 
.8118 
.  7229 

.7112 
.6438 
.6096 

•5733 
•5I05 

.1963 
.  1691 
.  1662 
.  1466 
.I3I8 

•1257 
.1087 
•1045 
.0951 
.  0829 

.0825 
.0707 
.0657 
.0598 
.0521 

.0499 
.0423 
•0413 
•0353 
.0328 

.0290 
.0260 
.0243 
.0206 
.0201 

.0164 
•0130 
.0100 

.0103 

.  00850 

.00815 

.  00665 
.  00646 

•00513 

.  00407 

.00323 

.00256 
.  00246 
.  00203 
.00181 

.00161 
.00128 

.00101 

.  00080 
.  000638 

.000615 
.  000507 
.000452 
.000401 
.000317 

126.  670 
109.090 
107.  100 
94.560 
85  .  ooo 

81.070 

7O.  120 
67  .  40O 
61.360 
53-400 

53-  19° 

45.600 
42.360 
38.600 
33.600 

32.176 
27.272 
26.650 
22.772 
21.150 

18.678 
16.770 
I5-659 
13-35° 
I3-035 

10.440 

8-367 
6.818 
6.580 
5-48o 

5-250 
4.288 
4.168 
3-3°8 

2.  626 

2.083 
1.652 
1.590 
I.3IO 
I.  167 

1.039 
.823 
•653 
•517 
.412 

•397 
•327 
.291 

.258 
.204 

250,000 
215,296 
211,600 
186,624 
167,805 

1  60,000 
I38,384 
133.079 
121,104 

105,534 

104,976 
90,000 

83,694 
76,176 

66,373 

63,504 
53,824 
52,633 
44,944 
41,742 

36,864 
33,io2 
30,976 
26,250 
25,600 

20,817 
16,509 
13,456 
13,094 
10,816 

10,381 
8,464 
8,234 
6,53° 
5,178 

4,107 

3,257 
3,i36 
2,583 
2,304 

2,048 
1,624 
1,288 

1,022 

810 

784 
643 
576 
5i° 
404 

756 

651 
641 

565 
508 

484 
419 
403 
366 
320 

317 
272 

253 

230 
2OI 

192 
l63 
159 
136 
126 

III 

IOO 

93-7 

79-5 
77-5 

63.0 
50.0 
40.7 
39-6 
32-8 

3r-4 
25.6 
24.9 
19.8 
15-7 

12.4 
9.86 

9-49 
7.82 

6-97 

6.  20 

4.92 
3.90 
3.09 
2.45 

2.40 

i-95 
1.70 

1-54 

1.22 

1126 
968 

955 
840 

756 

721 
623 
600 

545 
476 

472 
405 
377 
343 
299 

286 
243 
237 
203 
1  88 

165 
149 

139 
118 

"5 

93-9 

74-4 
60.6 

59-° 
48.8 

46.7 
38.1 
37-i 
29-5 
23-3 

18.5 
14.7 
14.1 
ii.  6 
10.4 

9.  22 

7-3° 
5-79 
4.60 

3-65 

3-57 
2.89 

2-53 

2.  29 

1.82 

.04141 
•  04805 
.04893 

•05550 
.06170 

.06472 
.07481 
.07780 
.08550 
.09811 

.  09870 
.1151 
.1237 
.1361 
.1560 

.1631 

•I925 
.1967 
.2308 
.  2480 

.2812 
.3128 
•3346 
•3944 
•4050 

•4973 
.6271 
.7700 
.7908 
•9570 

•9972 
i.  226 

1-257 
1.586 
1.999 

2.521 
3-179 
3-305 
4.009 
4.496 

5-055 
6-374 
8.038 
10.  14 
12.78 

13.21 
16.  12 
18.00 
20.  32 

25-63 

.1360 
•1576 
•  1605 
.1820 
•  2025 

.2123 
•2453 
•2552 
.  2804 
.3220 

.3240 
•3773 
•4059 
•4465 
.5116 

•5348 
•6313 
•  6450 
•757 
•  813 

.922 
1.026 
1.098 
1.294 
1.329 

2.632 
2-058 

2-525 
2.592 

3-i4o 

3.270 
4.020 
4.124 

5-200 

6.560 
8.260 

10.42 
10.84 

13-15 
14.74 

16.59 

20.90 

26.36 

33.25 
41.90 

43.30 

52.8 

59-0 
66.7 

84.0 

oooo 

5-° 

ooo 

0000 

ooo 

oo 
o 

oo 

o 

I 

I 

2 

3 

3 
4 

3 

5 

4 

6 

5 

7 

6 

8 
9* 

10* 

ii 

7 
8 

9 

12 

10 

13 

ii 

12 
13 

14 
15 

14* 
15* 

1  6* 

17 

16 

18 

17 
18 

19 
20 

21 

19* 
20* 

21* 

22 

22 

23 

24* 

25* 

23 
24 

*   Approximate  English  Equivalents  to  American  sizes. 


226  HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 

The  size  of  wire  chosen  shows  that  the  line  loss  is  greater  than  the  regulation, 
which  is  impractical.  As  this  is  a  cut  and  try  method,  such  conditions  appear  only 
in  checking  assumptions.  This  is  corrected  by  using  No.  ooo,  instead  of  No.  oo, 
which  was  tried  in  this  calculation. 

If  the  transmission  is  to  be  two  phase,  the  calculations  are  similar  except  that  each 
phase  carries  half  of  the  power. 

For  three  phase,  calculate  for  a  single  phase  to  carry  half  of  the  power,  and  each 
wire  is  the  size  determined. 

Transposition.  Excessive  inductive  effects  can  be  counteracted  by  transposing 
the  conductors.  In  the  final  transposition  the  phases  must  occupy  the  same  relative 
position  as  at  the  beginning.  The  number  of  transpositions  is  arbitrary;  for  instance, 
the  52,ooo-volt  line,  Gaucin-Seville,  Spain,  has  35  transpositions  throughout  its 
length  of  75  miles,  while  the  5o,ooo-volt  line  from  the  Uppenborn  plant  to  the  city  of 
Munich,  Germany,  has  but  three  transpositions  in  its  run  of  33  miles. 

Corona  Effect.  When  two  conductors  in  the  neighborhood  of  each  other  are 
charged  with  a  very  high  potential,  and  after  a  certain  value  of  electrical  pressure  has 
been  reached,  a  bluish  glow  surrounds  the  conductors;  this  glow  is  distinctly  visible 
in  the  dark.  Coincidently  with  the  appearance  of  this  glow,  loss  of  power  begins. 
A  further  increase  in  electromotive  force  produces  a  brush  discharge,  which  takes 
place,  not  from  surface  of  the  conductor,  but  from  the  external  limits  of  the  luminous 
envelope  surrounding  the  conductor.  This  brush  discharge  results  in  further 
augmentation  of  electrical  losses,  and  is  usually  accompanied  by  a  hissing  or  crackling 
noise.  It  is  intermittent  in  character  and  is  reddish  violet  in  color.  The  name 
"corona"  has  been  given  to  the  combined  luminous  manifestations  of  initial  glow 
and  subsequent  brush  discharge. 

If  the  electromotive  force  were  carried  still  higher,  the  current  would  jump 
through  the  air  from  one  conductor  to  the  adjacent  one;  but  in  the  case  of  wide 
separations,  such  as  are  usual,  this  would  require  an  electromotive  force  greater  than 
anything  either  contemplated  or  necessary.  In  the  case  of  arcing,  the  line  is  short- 
circuited,  and  continued  arcing  would  mean  a  cessation  of  power  supply. 

Since  the  appearance  of  the  corona  and  the  brush  discharge  represent  power 
losses  which  may  be  of  considerable  magnitude,  it  is  desirable  that  the  line  be  so 
proportioned  and  operated  at  such  potential  as  to  avoid  them,  and  this  is  particularly 
necessary  in  the  case  of  transmission  systems  which  supply  only  a  small  amount  of 
power,  because  the  energy  loss  due  to  the  corona  effect  is  independent  of  the  energy 
transmitted  over  the  line,  being  fixed  by  the  voltage  and  not  by  the  energy.  There- 
fore, while  the  losses  might  represent  a  small  percentage  of  a  large  amount  of  power, 
they  would  be  a  large  percentage  of  a  small  amount. 

A  proper  investigation  of  this  subject  requires  first  a  consideration  of  electro- 
static phenomena  in  general.  In  a  paper  l  by  Lamar  Lyndon,  who  has  collated 
existing  data  on  the  subject  by  authorities,  Mershon,  Ryan  and  Steinmetz,  the 
following  conclusions  are  enumerated : 

1  The  Corona  Effect  and  its  Influence  on  the  Design  of  High  Tension  Transmission  Lines.  Philadelphia 
Section,  Am.  Inst.  E.  E.,  Nov.  9,  1908. 


ELECTRICAL   TRANSMISSION.  227 

1.  The  critical  voltage  is  dependent  on  the  diameter  of  the  conductors,  their 
distance    apart    and    atmospheric   conditions,    increasing   with   both   diameter    and 
separation  of  the  conductors. 

2.  After  the  critical  voltage  is  reached  the  losses  increase  very  rapidly  with 
increase  in  voltage. 

3.  The  critical  voltage  and  the  magnitude  of  the  losses  after  it  is  obtained  are 
affected  by  atmospheric  conditions,  and  therefore  varies  with  the  locality  and  season 
of  the  year. 

4.  In  the  same  section  of  country  a  voltage  which  is  normally  below  the  crit- 
ical  point   may  be   at  times   above  the  critical  voltage  with  changes  in  weather 
conditions. 

5.  Smoke,  fog,  moisture  or  floating  particles  increase  the  losses,  while  the  effect 
of  rain  is  appreciable. 

6.  With  increase  in  separation  of  conductors  the  regulation  and  power  factor 
are  diminished. 

7.  A  separation  of  ten  feet  between  wires  is  as  great  as  is  commercial  or  desirable. 

8.  The  same  law  applies  to  cables  as  to  solid  wires,  the  diameter  of  the  cable 
being  effective  diameter  of  the  conductor. 

9.  The  losses  appear  to  be  independent  of  the  material  of  which  the  conductors 
are  composed. 

10.  The  losses  and  the  critical  voltage  appear  to  decrease  slightly  with  the 
frequency. 

11.  A  transmission  line  should  be  designed  for  the  atmospheric  conditions  that 
may  obtain  in  the  locality  through  which  it  passes. 

12.  All  corona  formation  and  losses  depend  on  the  maximum  value  of  the  volt- 
age waves.     Therefore  the  ratio  of  the  maximum  to  the  mean  value  should  be 
definitely  known  to  properly  design  a  transmission  system. 

13.  The  limiting  voltage  (effective)  which  may  be  applied  to  a  circuit  of  No.  o 
wires,  seven  feet  apart,  with  a  maximum  vapor  product  of  0.4,  and  keep  down  the 
line  loss  due  to  the  corona  within  three  kilowatts  per  mile,  is  approximately  110,000 
volts. 

14.  High-tension    transmission    systems    working    under    potentials    exceeding 
150,000  volts  must  have  the  wires  covered  with  some  insulating  material  having  a 
greater  dielectric  strength  than  air,  or  use  conductors  of  abnormally  great  diameter. 

The  paper  shows  that  under  usual  atmospheric  conditions,  which  prevail  through- 
out the  United  States,  the  following  formula  is  applicable: 

E  =  148,000  X  (r  X  .07)  X  Iog10 — >  in  which 

r 

E  =  effective  voltage  at  which  the  corona  will  form  and  loss  begin. 
r  =  radius  of  conductors  in  inches. 
D  =  distance  apart  of  conductors  in  inches. 

Obviously  the  voltage  applied  should  be  less  than  that  at  which  the  corona  is 
formed. 


228 


HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 


From  the  formula,  it  is  evident  that  after  a  separation  of  100  times  the  radius  of 
the  conductors  has  been  reached,  any  further  separation  is  practically  negligible  in  its 
effect,  and  with  very  high  potentials  the  only  remedy  against  corona  losses  is  the 
increase  in  the  diameter  of  the  wire.  A  practical  example  shows,  that  for  a 
potential  of  250,000  volts  and  a  conductor  separation  of  90  inches,  the  diameter 
of  the  conductors  must  be  1.5  inches. 

Such  a  conductor  would  contain  far  too  much  metal  to  be  easily  supported  in  the 
air  or  for  the  necessary  conductivity.  Therefore  it  is  believed,  that  a  large  jute  or 
hemp  core  overlaid  with  a  thin  sheath  of  stranded  copper  or  aluminum  is  the  proper 
conductor  to  use  on  high-tension  lines;  the  metal  sheath  being  of  such  a  thickness  as 
will  give  the  requisite  cross  section  to  transmit  the  energy  of  the  system. 

POLE   AND    TOWER    CONSTRUCTION. 

For  carrying  the  conductors  of   a  transmission  system,  the  following  pole  and 
tower  construction  is  used: 
i.    Wooden  poles. 

Concreted  wooden  poles. 
Reinforced  concrete  poles  and  towers. 
Steel  pipe  poles  and  towers. 
Structural  steel  towers. 
Of  this  wide  variation  wooden  pole  and  structural  steel  towers  are  chiefly  used; 
however,  the  different  types  will  be  successively  treated. 


_t_ 

a 

i 

sa- 

P 

:    ! 

1 

j 

r  • 

i  • 

<"n* 

1 

WW 

1 

«•* 
i  - 

FIG.  i. — Types  of  poles  used  at  the  50,000  V.  Line  of  Taylor's  Falls,  Minneapolis  Power 

Transmission. 

WOODEN   AND    CONCRETE    POLES. 

Wooden  Poles.  Where  the  transmission  line  runs  through  a  section  or  in  the 
vicinity  of  a  forest  district,  where  poles  may  be  cut,  the  wooden  pole  is  more  apt  to 
be  chosen  because  of  its  cheapness,  little  or  no  transportation,  and  ease  of  erection. 
Another  advantage  is,  that  they  offer  better  protection  for  the  community,  because 
they  are  insulators.  The  disadvantages  in  the  use  of  wooden  poles  are,  that  they 


ELECTRICAL  TRANSMISSION. 


229 


decay  very  rapidly;  more  insulators  are  required  owing  to  the  short  spacing;  they  are 
readily  destroyed  by  storms,  lightning  and  fire. 

Taking  the  given  disadvantages  into  consideration,  which  in  many  instances 
outstrip  the  advantages,  for  instance  the  first  cost,  one  will  find  to-day  in  thickly 
wooded  sections,  steel  towers  carrying  the  transmission  line  conductors. 


. 
'*- 


_I_U 

FIG.  2. — Typical  Three  Phase  Circuit  Poles. 

The  ordinary  type  of  line  construction  is  a  single  pole  with  cross  arms  as  seen  in 
Figs,  i  and  2.  Other  types  are  the  "  A  "  frame  and  "  H  "  frame,  both  of  which 
require  two  poles.  The  latter  types  must  be  properly  braced  and  securely  bolted,  to 
prevent  any  deformation  due  to  excessive  stresses.  These  structures  are,  accord- 
ing to  A.  C.  Wade1  who  made  exhaustive  tests  on  the  various  types  of  wooden  poles 
and  frames,  3  to  4.5  times  as  strong  as  a  single  pole. 

Strength  of  Wooden  Poles.  For  calculating  the  stresses  in  wooden  poles  the  fol- 
lowing formula  may  be  used. 

M=  — 


M  =  bending  moment. 
R  =  radius  of  section  at  ground  level. 
5  =  strength  of  wood  per  square  inch. 
H  =  height  above  ground  of  force  applied. 

This  formula  applies  only  to  a  pole  of  uniform  cross  section.  In  the  usual  case, 
the  pole  is  tapered  and  will  break  about  half-way  between  the  ground  and  cross  arm. 

Kind  of  Wood.  The  kind  of  wood  depends  upon  the  locality  through  which  the 
line  runs,  the  cost  and  factor  of  safety  desired.  In  western  transmission  lines,  spruce 
and  fir  are  much  used,  while  in  California,  redwood  is  prevalent.  Cedar  and  chest- 
nut are  also  used;  the  former  is  expensive  and  has  great  durability.  Pine  is  the  most 
extensively  used  in  pole  line  construction,  owing  to  its  cheapness,  but  has  the  dis- 
advantage of  a  short  life  and  inferior  strength. 

1  The  Use  of  Wooden  Poles  for  Overhead  Power  Transmission,  by  A.  C.  Wade.  Inst.  oj  Elec.  Engin- 
eers of  Great  Britain,  May  2,  1907. 


230  HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 


FIG.  2A. — Wooden  Towers  of  the  "A"  Frame  Type,  with  Disconnecting  Switches. 


ELECTRICAL  TRANSMISSION. 


231 


Poles  come  in  lengths  varying  from  30  to  60  feet;  the  butt  diameters  vary  from 
10  to  12  inches,  and  the  top  7  to  9  inches.  They  are  set  with  one-sixth  to  one-seventh 
of  their  length  in  the  ground,  and  sometimes  as  high  as  one-eighth. 

Cross  Arms.  The  cross  arms  are  made  of  first-class  wood,  such  as  chestnut,  white 
oak,  cedar,  redwood,  red  or  yellow  pine.  Arms  8  feet  long  are  4  by  5  inches  in  cross 
section,  3-foot  arms  about  3  by  4  inches.  For  long-span  lines,  the  cross  arms  are 
sometimes  made  6  by  6  inches.  The  cross  arm  must  be  properly  braced  to  stand 
stresses  applied  on  same.  They  are 
fastened  to  the  pole  by  means  of  lag  screws 
or  bolts  usually  f  to  f  inch  in  diameter. 
As  a  protection  against  splitting,  the  cross  ^ 

arms  are  through  bolted  on  both  sides  of 
the  pin.  Experience  has  proven  that 
certain  cross  arms  split  at  a  stress  of  1200 
pounds,  while  when  through  bolts  were 
used,  the  cross  arm  failed  to  yield  at  2000 
pounds.  For  long  stretches  and  on  corners, 
the  cross  arms  must  be  doubled,  to  stand 
the  stresses.  For  medium  spans  where 
single  cross  arms  are  used,  they  must  face 
the  same  direction  on  alternate  poles,  while 
the  intermediate  cross  arms  must  face  the 
opposite  direction. 

Life  of  Wooden  Poles.  The  life  of  a 
pole  depends  on  the  nature  of  the  wood, 
chemical  treatment,  and  climatic  conditions, 
also  character  of  soil.  Redwood  and  cedar 
poles  under  favorable  conditions  may  last 

20  years,  while  the  life  of  chestnut  is  about 

.  TIG.  3. — Arrangement  of  Cross  Arm  and 

15    years,    and    that    of    pine    and    white  Guard  Wire      40>000  v   Line 

cedar,    10   years.      When   chemical   treat- 
ment is  applied,  the  life,  of  course,  will  be  materially  increased.     Where  poles  are 
set  in  marshy  ground,  or  ground  which  is  alternately  wet  and  dry,  the  life  of  the 
pole  is  correspondingly  decreased. 

Preservation  of  Wooden  Poles.  To  lengthen  the  life  of  a  wooden  pole  it  must  be 
properly  preserved;  it  must  be  treated  with  some  chemical  compound.  The  simplest 
and  least  expensive  way  is  to  paint  the  top  and  butt,  at  least  two  feet  above  the  ground 
level,  with  tar  or  creosote.  More  thorough  methods  of  treating  poles  are  done  by 
special  concerns,  who  treat  the  entire  pole.  The  treatments  are  more  or  less  iden- 
tical, that  is,  the  poles  are  placed  en  masse  in  inclosed  cylinders  and  subjected  to 
intense  heat  (usually  steam),  varying  from  200  to  250°  F.;  then  they  are  shifted  to 
vacuum  cylinders  to  remove  the  sap,  after  which  they  receive  chemical  treatment 
in  a  cylinder  under  pressure.  The  cross  arms  should  be  subjected  to  the  same 
treatment.  All  cutting  and  trimming  of  poles  must  be  done  before  they  are  sub- 


232  HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 

jected  to  chemical  treatment.  Where  drilling  or  cutting  has  to  be  done  in  the  field, 
after  treatment,  these  places  must  again  be  treated  with  chemicals,  which  are  usually 
tar  or  creosote.  The  top  of  the  pole  must  be  beveled  or  a  cast  iron  cap  provided. 

Pole  Line  Construction.  To  secure  correct  alignment,  the  location  of  the  poles 
must  be  made  with  the  aid  of  a  transit,  and  the  pole  itself  must  be  lined  up  with  a 
plumb  bob.  The  poles  must  be  correctly  distributed  according  to  length.  The 
cross  arms  may  be  mounted  before  the  pole  is  set,  and  frequently  the  insulators  are 
mounted  at  the  same  time.  Poles  up  to  40  feet  in  length  are  usually  erected  by 
about  6  men  with  pikes,  while  poles  above  this,  are  preferably  erected  by  means  of  a 
portable  derrick  and  a  team  of  horses,  otherwise  the  services  of  10  to  12  men  are 
required.  The  poles  are  set  either  in  concrete  blocks  or  directly  in  the  ground;  in  the 
latter  case,  they  are  frequently  provided  with  a  cross  member  to  resist  uplift.  Where 
poles  have  to  be  set  in  marshy  or  swampy  ground,  it  is  frequently  impossible  to  set 
them  without  very  heavy  footbracing,  consisting  of  bracing  with  a  semi-crib  con- 
struction filled  with  ballast. 

Guys.  Where  the  line  is  dead-ended,  and  on  sharp  turns,  poles  are  guyed  where 
permissible.  This  practice  is  not  to  be  recommended  with  steel  towers,  because,  as 
the  expenditure  is  made  for  a  structural  steel  tower,  the  structure  should  be  made 
stable  enough  to  resist  any  strain  or  stress  applied  to  same;  otherwise  wooden  poles 
may  be  erected. 

The  methods  commonly  employed  in  guying  are  to  bury  a  "dead  man"  in  the 
ground  or  use  some  of  the  patent  guy  anchors  now  on  the  market.  The  "dead  man" 
is  a  pole  of  short  length  buried  in  the  ground  some  distance  from  the  pole,  and  so 
placed  that  it  lies  normal  to  the  direction  of  the  guy  wire  fastened  to  it.  The  patent 
anchors  are  so  made  that  little  or  no  excavation  is  necessary  to  bury  them.  Other 
advantages  of  patent  anchors  are  the  ease  of  transportation,  erection  and  removing 
same;  several  anchors  can  be  readily  applied  to  one  guy. 

Concreted  Wooden  Poles.  The  concreted  wooden  pole  has  not  been  used  to  any 
great  extent.  It  has  only  been  used,  to  the  writer's  knowledge,  in  Switzerland.  It 
consists  of  an  ordinary  pole  covered  with  a  layer  about  one  inch  thick  of  concrete 
mortar.  As  this  coating  covers  the  entire  pole,  its  life  is  made  practically  indefinite 
and  the  strength  of  the  poles  is  materially  increased,  and  so  fewer  poles  and  insulators 
are  needed.  The  concrete  block  setting  frequently  required  is  eliminated. 

Reinforced  Concrete  Poles.  The  ordinary  reinforced  concrete  pole  is  of  similar 
construction  as  most  types  of  concrete  piles.  They  are  made  solid  or  hollow,  in 
cross,  square  or  circular  cross  sections,  and  are  reinforced  by  a  number  of  iron  or 
steel  rods  according  to  the  strength  of  pole  desired.  As  these  poles  may  be  made  for 
any  practical  strength  and  length,  it  is  a  very  convenient  type  of  pole,  particularly  as 
they  are  readily  made  in  the  field. 

A  type  of  reinforced  concrete  pole,  developed  and  used  to  some  extent  in 
Germany  and  recently  introduced  from  Switzerland  into  England,1  are  hollow 
and  tapering,  in  lengths  up  to  about  40  feet.  The  machine  is  capable  of  making 
poles  of  any  size  and  lengths  within  the  limits  of  40  feet  long  and  2  feet  in  diameter. 

1  Electrician,  London,  July  31,  1908. 


ELECTRICAL  TRANSMISSION.  233 

In  the  process  of  manufacture,  a  long  sheet  iron  core  is  mounted  on  two  trestles,  run- 
ning on  rails,  so  as  to  be  capable  of  rotational  and  longitudinal  movements.  Upon 
this  core,  small  longitudinal  steel  rods  are  fixed.  The  core  is  drawn  through  the 
machine,  which  is  stationary. 

Concrete  made  of  clean  screened  grit  and  Portland  cement  is  mixed  dry  in  a 
mechanical  mixer  and  discharged  through  a  chute  into  a  hopper  or  drum  in  which 
rotating  paddle  wheels  regularly  discharge  the  concrete  upon  a  bandage  of  coarse 
webbing  laid  on  a  conveyor  belt,  that  takes  one  lap  around  the  core.  This  con- 
tinuous traveling  conveyor  belt  is  stretched  so  that  the  concrete  is  wrapped  about  the 
core  under  great  pressure.  As  the  core  issues  beyond  the  conveyor  belt,  wire  is  fed 
spirally  around  it  so  as  to  press  into  the  concrete  wrapping,  and  small  rollers  then 
apply  great  pressure  by  working  on  the  webbing,  the  slack  of  which,  caused  by  the 
reduction  in  diameter  resulting  from  this  pressure,  is  taken  up  by  another  device.  . 

The  core  as  it  issues  from  the  machine  is  wrapped  about  spirally  with  a  bandage 
of  cloth.  The  machine  pulls  the  trestles  forward  with  the  suspended  core  as  the 
concrete  is  wrapped  on,  and  when  the  core  has  passed  completely  through  the 
machine  it  is  lifted  by  an  overhead  crane  and  laid  to  one  side  to  harden.  It  is  kept 
constantly  damp  so  as  to  secure  the  maximum  hardness.  In  about  twelve  hours 
the  interior  sheet  metal  core  is  reduced  in  diameter  by  means  of  a  screw  attachment 
inside  and  withdrawn.  After  hardening  six  days  the  bandage  of  webbing  is  removed, 
and  the  whole  is  then  complete  for  setting. 

The  poles  are  estimated  to  have  a  life  of  fifty  years,  and  during  that  time  will  cost 
nothing  for  maintenance.  On  this  basis  the  total  cost  of  a  pole  at  the  end  of  fifty 
years  is  estimated  to  be  $20.00  for  the  concrete  pole,  $50.00  for  an  iron  pole  and  $53.00 
for  a  wooden  pole,  all  including  maintenance,  repairs  and  renewals.  This  is  for  a 
29-foot  pole.  For  a  36-foot  pole  for  transmission  service  and  for  the  same  period, 
the  corresponding  figures  are:  for  the  concrete  pole,  $26.00;  for  the  iron  pole,  $60.00; 
and  for  the  wooden  pole,  $68.50.  Any  desired  amount  of  ornamentation  may  be 
given  to  the  poles.  Some  tests  on  a  pole  of  this  type,  32  feet  9  inches  long,  showed  a 
deflection  of  2f  inches  with  a  tensile  strain  of  15,000  pounds. 

Tests  on  a  Siegwart,  lo-meter  pole  (39.3  feet)  show  the  following  results:  with  a 
pull  of  880  pounds,  the  deflection  was  i.i  inch,  which  increased  to  3.5  inches  with 
a  pull  of  1540  pounds;  the  permanent  deflection  being  2.5  inches,  owing  to  the  fact 
that  the  strain  was  slowly  released.  In  another  test,  with  a  pull  of  1540  pounds,  a 
deflection  of  2.75  inches  was  produced;  when  suddenly  released,  the  top  of  the  pole 
assumed  its  original  position.  A  third  test,  with  the  application  of  a  pull  of  2200 
pounds  and  6.1  inches  deflection,  showed  a  permanent  set  of  4.72  inches  with  a 
gradual  release  of  the  pull.  In  all  of  these  tests  no  signs  of  fracture  or  cracks  appeared. 

Steel  Pipe  Towers.  The  simplest  form  of  a  steel  pipe  pole  is  that  of  a  single 
pipe  with  cross  arms.  For  more  rigid  and  higher  constructions,  three-legged  poles 
have  been  constructed.  Owing  to  the  length,  each  leg  is  made  in  sections  and  coupled 
by  nipples,  the  legs  being  cross-braced  by  angle  irons  and  rods.  Such  towers  have 
been  constructed  for  the  Ontario  Power  Company,  but  this  type  is  now  obsolete;  it 
has  been  superseded  by  structural  steel  towers,  which  are  more  economical. 


234 


HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 


[L  151.75 

C.Urt  ft  3  *Cntt  -Ana 

Clint  of  t"Cmi-Arm_  ][il  EU4 0£ 


l     4  {'  !'    *!  I!  «     K     8 


f/3J5 


Section  A-B. 


ENC.NTN5. 


FIG.  i. — Reinforced  Concrete  Tower  and  Foundation. 

REINFORCED    CONCRETE   TOWERS. 

Where  special  long  and  high  spans  are  required,  high  towers  are  necessary.  A 
few  of  such  towers  have  recently  been  built  of  reinforced  concrete;  for  instance  those 
at  Brownsville,  Penn.,1  erected  by  the  West  Pennsylvania  Railway  Company,  for 
carrying  a  transmission  line  across  the  Monongahela  River.  The  main  tower  rises 
150  feet  above  its  foundation;  the  second  tower  is  but  55  feet  high  and  located 

1  Reinforced  Concrete  Towers  for  High  Potential  Transmission  Lines,  by  F.  W.  Scheidenhelm.  Engineer- 
ing News,  May  2,  1907. 


ELECTRICAL  TRANSMISSION. 


230  feet  behind  the  first,  and  acts  as  an  anchorage,  taking  the  dwct,  strain  of  'the 
main  span  which  is  1014  feet.  They  are  reinforced  as  follows: 

For  reinforcement  old  T-rails  were  used.  All  of  the  rails  forming  the  vertical 
reinforcement  were  of  60  pounds  section.  The  safe  unit  stresses  were  cut  down  to 
allow  for  the  wear  which  many  of  the  rails  showed.  Incidentally,  the  use  of  rails 
solved  the  problem  of  the  end-to-end  connection  in  the  case  of  the  vertical  reinforce- 
ment, for  the  ordinary  spliced-plate  joint  thus  became  possible.  On  the  other  hand, 
the  large  cross  section  of  each  rail  was  a  disadvantage.  In  certain  sections  of  the 
towers,  for  instance,  it  was  necessary,  under  the  circumstances,  to  insert  the  full  cross 
section  of  a  rail,  even  though  only  a  fraction  of  it  was  required  by  the  stress  to  be 
carried.  The  base  section  of  the  main  tower  contains  twelve  6o-pound  rails,  three 
being  placed  at  each  corner,  while  the  base  section  of  the  anchorage  tower  contains 
ten  rails  in  the  tension  side  and  two  in  compression.  Thus  the  main  tower  base  con- 
tains 1.73  per  cent  of  steel,  and  the  anchorage  tower  base  1.25  per  cent. 

In  addition  to  the  vertical  reinforcement  of  rails,  a  spiral  winding  of  three-eighths 
cable  was  used.  Two  spirals  were  wound,  i  foot  apart,  thus  giving  a  2-foot  pitch. 
Tie  wires  secured  the  spiral  winding  to  the  vertical  reinforcement,  the  concrete 
being  i  :  2.5  :  5  for  the  footings  and  1:2.5:4  for  the  tower. 


STEEL   TOWERS. 

With  the  introduction  of  high-tension  transmission,  wooden  poles  are  fast  being 
substituted  by  structural  steel  towers.  The  majority  of  transmission  lines  now  in 
use  employ  this  type  of  tower.  They  are  made  up  of  angles,  channels  and  lattice 
construction,  and  in  two,  three  and  four-legged  type. 

All  towers  for  carrying  transmission  lines  have  to  be  calculated  to  withstand  the 
following  general  conditions: 

They  must  be  self-supporting,  strong  enough  to  carry  the  line  conductors  and  to 
resist  the  wind  pressure  on  the  conductors  and  tower  itself.  To  this  must  be  added 
the  load  due  to  sleet,  and  the  effects  of  temperature  changes,  as  well  as  a  factor  of 
safety  to  guard  against  accident,  such  as  the  breaking  of  one  or  more  conductors. 

Wind  Pressure  on  Structures.  The  records  of  the  United  States  Weather  Bureau 
are  available  as  an  aid  in  estimating  the  maximum  velocity  to  be  expected  in  a  given 
locality.  These  published  velocities  are  not  accurate,  but  must  be  corrected  by  a 
correction  table,  which  may  be  obtained  from  the  Weather  Bureau  and  is  as 
follows  : 

TABLE    I.  —  CORRECTED    WIND    VELOCITIES. 


Indicated 

Actual 

Indicated 

Actual 

velocity. 

velocity. 

velocity. 

velocity. 

10 

9.6 

60 

48 

20 

I7.8 

70 

55-2 

3° 

25-7 

80 

62.  2 

40 

33-3 

90 

69.  2 

5° 

40.8 

IOO 

76.2 

236         ,  HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 


'The  relation  between  wind  velocity  and  the  pressure  produced  by  the  wind  on  a 
plane  surface  normal  to  the  direction  of  the  wind  is  given  by  Scholes1  in  the  following: 

M  =  KV\ 

M  =  pressure  in  pounds  per  square  foot. 

V  =  wind  velocity  in  miles  per  hour. 

K  =  constant. 

Experiments  in  general,  indicate  that  this  form  of  equation  is  correct,  but  differ 
as  to  the  proper  value  of  K.  According  to  tests  by  the  Weather  Bureau,  K  —  0.004, 
which  is  probably  the  most  reliable  figure. 

Experiments  indicate  in  general,  higher  pressures  are  to  be  expected  at  the  top 
of  a  tower  than  near  the  ground,  but  little  is  known  as  to  how  the  pressure  is  dis- 
tributed. There  is  considerable  doubt  as  to  what  should  properly  be  considered 
the  exposed  area  of  a  structure;  it  is  certain,  however,  that  both  faces  are  not,  in 
general,  subject  to  the  same  pressure.  It  is  usually  considered  that  a  reduction  factor 
of  0.5  should  be  used  in  figuring  the  wind  pressure  per  square  foot,  of  projected 
area  of  cylindrical  surfaces.  The  wide  use  which  has  been  given  this  factor  is  its 
principal  recommendation. 

It  appears,  therefore,  that  it  would  be  good  practice  in  transmission-line  con- 
struction to  specify  that  the  poles  or  towers  should,  in  addition  to  their  other  prop- 
erties, have  strength  to  resist  loads  on  their  members  due  to  a  wind  pressure  of  40 
pounds  per  square  foot,  with  a  factor  of  safety  from  1.5  to  2,  based  on  actual  test. 
Such  a  structure  would  be  suitable  for  locations  where  the  winds  are  high;  in  other 
locations  these  figures  would  be  reduced  by  judgment,  aided  by  a  consultation  of 
the  weather  reports  and  other  such  data. 

Wind  Pressure  on  Conductors.  It  is  not  necessary  to  allow  as  high  a  pressure 
on  the  conductors  of  long  spans  as  on  the  tower  itself;  however,  there  are  little  definite 
data  available  for  such  calculation,  but  a  value  of  30  pounds  per  square  foot  is  usually 
chosen  for  localities  where  the  wind  velocities  are  high.  In  order  to  keep  the  stresses 
of  a  conductor  within  its  elastic  limit,  a  factor  of  safety  of  at  least  2  should  be  chosen. 

Sleet.  Where  the  transmission  line  runs  in  temperate  zones,  the  weight  of  sleet 
must  be  considered.  (Specific  Gravity  of  ice  is  0.92,  or  57.4  pounds  per  cubic  foot.) 
Although  sleet  collects  in  the  middle  of  the  span  with  a  greater  thickness  than  near 
the  towers,  the  usual  practice  is  to  allow  0.5  inch  thickness,  so  that  the  diameter  of 
the  cable  is  increased  one  inch.  As  the  sleet  is  apt  to  remain  several  days,  during 
which  time  high  wind  storms  may  occur,  it  is  necessary,  therefore,  that  when  calcu- 
lating the  wind  pressure,  the  increased  diameter  must  be  considered. 

Foundations.  The  foundations  of  towers  are  made  of  concrete,  or  cross  members 
are  buried  in  the  ground  under  heavy  ballast.  The  former  is  the  most  common 
method.  They  must  be  heavy  enough,  or  so  designed  to  resist  the  uplift,  equal  to 
the  weight  of  the  foundation  plus  the  weight  of  earth  taken  at  the  angle  of  repose. 

1  Fundamental  Considerations  Governing  the  Design  of  Transmission  Line  Structures,  by  D.  R.  Scholes. 
Am.  Inst.  of  E.  E.,  Atlantic  City,  N.  J.,  June  30,  1908. 


ELECTRICAL  TRANSMISSION 


A.E.&M, 


In  designing  towers,  tests  of  the  soil  should  be  made  to  determine  its  holding  power 
and  carrying  capacity.  Many  of  the  foundations  for  recent  installations  arc  of 
reinforced  concrete.  They  have  the  form  of  an  inverted  T.  The  horizontal  cross  arm 
gives  additional  anchorage  to  resist  uplift.  Another  advantage  of  the  reinforced 
concrete  foundations  is,  as  they  are  comparatively  light  they  may  be  made  on  one  or 
more  sections  of  the  line  and  transported  to  place. 

Portability.  It  is  but  natural  that  most  transmission  lines  run  through  sections  of 
country  where  transportation  facilities  are  seriously  handicapped.  Besides  this,  the 
towers  for  modern  transmission  lines  are  of  such  large  size  that  it  is  difficult  to  ship 
them  by  rail  or  water,  therefore  it  is  necessary 
to  design  them  so  that  they  can  be  transported 
in  pieces,  known  as  "knocked  down."  The 
members  of  the  towers  can  be  readily  transported 
on  the  backs  of  burros  or  mules. 

Two-Legged  Towers.  As  stated,  towers  are 
designed  with  two,  three  or  four  legs.  The 
two-leg  type  is  made  of  two  channels  or  I-beams 
cither  in  H  or  A  form,  and  cross-braced.  With 
this  type  of  tower  carrying  three  conductors,  the 
possibility  is,  that  if  two  or  all  conductors  break, 
the  adjacent  towers  may  be  deflected,  and  like- 
wise the  next  towers  may  be  somewhat  affected. 
In  order  to  overcome  the  possibility  of  several 
towers  being  affected,  every  fourth  or  fifth  tower 
may  be  rigidly  guyed. 

This  type  of  tower  for  three  conductors  is 
sufficiently  strong  in  the  transverse  direction, 
and  for  short  spans  in  general;  however,  when 
long  spans  come  into  consideration,  they  are 
weak  in  the  longitudinal  direction.  When,  how- 
ever, the  tower  carries  six  or  more  conductors, 
as,  for  instance,  in  the  later  described  Italian 
tower  at  Tretzo,  where  twelve  conductors  are 
carried  on  a  tower,  the  breakage  of  a  few  con 
ductors  amounts  to  but  a  comparatively  small 
per  cent  of  the  total,  and  the  tower  is  little  or 
none  affected.  As  stated,  this  tower  has  been 
erected  to  carry  spans  up  to  600  feet. 

The  standard  towers  of  the  75-mile,  52,000- 
volt  Gaucin-Seville,  Spain,  transmission  system, 

are  made  in  H-frame  of  two  channels  with  diagonal  bracing  of  flat  bars,  and 
accommodate  two  3-phase  circuits. 

Another  two-legged  tower  transmission  system  is  that  for  Moosburg  to  Munich, 
Germany,  a  distance  of  32  miles.     These  towers  are  of  the  A-frame  type,  and  carry 


FIG.  i. — Two-Legged  37-Foot 
Transmission  Tower,  Used  in 
Switzerland  and  Italy. 


238 


HYDROELECTRIC   DEVELOPMENTS   AND   ENGINEERING. 


a  single  3-phase  circuit  and  two  telephone  lines.     One  conductor  is  carried  on  the 
peak  of  the  frame,  and  the  other  two  on  a  common  cross  arm. 

Before  the  contracts  for  the  transmission  structures  were  let,  tests  were  con- 
ducted on  (i)  wooden  A-frame  structure;  (2)  steel  tube  poles;  (3)  Mannsmann  tube 
poles;  (4)  latticed  tower  of  angle  iron;  (5)  I-beam  A-frame. 


i. 


FIG.  2. — Types  of  Poles  and  Towers  tested  before  Contract  was  let  for  5o,ooo-volt 
Transmission  System,  Moosburg,  Munich,  Germany. 

The  following  table  gives  a  comparison  of  the  tests  on  the  above  structures, 
together  with  the  prices  in  marks.  The  structures  are  tabulated  successively  as 
above  numbered,  and  are  expressed  in  the  metric  system  and  serve  for  ready 
comparison. 


.•*v 

i 

o 

3 

4 

5 

Res.  -Mom.  in  line  direction  in  cm3  

ooo 

^2.  2 

•Ji.  o 

2C2 

C2 

Res.  -Mom.  in  transverse  direction  in  cm3  
Safe  load  in  kilograms  

5440 

IOO 

32.2 

l8oO 

33-9 

2  2OO 

353 
870 

5o 

1800 

Cost  in  marks  including  two  cross  arms  

7C.  2O 

4O.  ?? 

4C.  2O 

8O.  7O 

40.  oo 

It  will  be  noticed  that  the  wooden  structure  was  not  favorable,  especially  as  the 
line  passes  through  marshes,  and  the  life  of  a  wooden  structure  is  short.  The 
I-beam  structure  outstripped  the  others  regarding  safe  load  and  price,  which  is  the 
reason  why  this  structure  was  adopted. 

The  standard  tower  is  23  feet  to  the  lower  insulator,  and  is  embedded  5  feet  deep 
in  a  concrete  block,  and  carries  three  solid  copper  conductors;  the  standard  spacing 
is  165  feet. 

The  towers  are  made  up  of  two  I-beams  braced  at  three  points;  as  the  cross  sec- 
tions of  the  conductors  vary  from  70  to  16  square  millimeters,  the  size  of  the  I-beams 
varies  from  5.5  to  3.5  inches  correspondingly.  None  of  them  are  provided  with 


ELECTRICAL  TRANSMISSION. 


239 


FIG.  3. — Aermotor  Four-Legged  Twin  Tower  with  Ground  Wire  Pin  as  used  by  the  Southern 
Power  Co.,  Charlotte,  N.  C.     This  Type  is  a  Combination  of  Two  Three-Legged  Towers. 


240 


HYDROELECTRIC    DEVELOPMENTS   AND   ENGINEERING. 


guy  wires. 


There  is  a  total  of   2260   towers,   which   were  erected   by  two  gan<ys7 

each   consisting  of  40    men  capa- 
ble   of    erecting,   on    the   average, 

nearly 


20 


da.      As 


FIG.  4. — Detail  of  45-Foot  Angle  Iron  Tower  at 
Syracuse,  N.  Y. 


towers  per 
the  whole  course  follows  the 
river  Isar,  all  of  the  material 
was  conveniently  transported  on 
boats. 

Three-Legged  Towers.  This  type 
of  tower  is  used  for  small  conduc- 
tors carrying  not  more  than  33,000 
volts.  They  are  economical  in  de- 
sign, and  made  up  of  light  angle 
irons.  Owing  to  the  triangular  sec- 
tion, the  stresses  due  to  the  conduc- 
tors only,  are  distributed  unequally 
on  the  three  legs;  the  tower  itself 
cannot  be  surpassed  by  any  other 
type. 

A  tower  possessing  some  of  the 
featuresof  a  three-leg  type,  yet  hav- 
ing a  rectangular  plan  on  its  base, 
is  the  combination  of  two  3-pole 
towers,  and  is  known  as  the  "  twin 
tower."  These  towers  are  intercon- 
nected at  a  common  point,  as  seen 
in  Fig.  3. 

Four-Legged  Towers.  The  towers 
in  which  the  stresses,  transverse  as 
well  as  longitudinal,  are  equally 
distributed,  are  of  the  four-leg  type. 
They  are  made  up  of  angle  iron 
and  frequently  cross-braced  with 
rods  instead  of  angle  iron,  and  in 
almost  all  cases  are  designed  to 
withstand  the  stresses  set  up  when 
two-thirds  of  the  conductors  break; 
for  further  security,  they  are  double 
guyed  at  intervals,  as  has  been 
done  on  the  Niagara,  Lockport 
and  Ontario  Company's  transmis- 
sion line;  this  precaution,  however, 
is  only  necessary  when  all  the 


cables  should  break  at  once.     Such  occurrences  rarely  happen. 


ELECTRICAL  TRANSMISSION. 


241 


Tretzo  Tower.  The  first  structural  steel  towers  are  found  in  Switzerland  and 
Italy,  and  sorfie  of  the  recent  transmission  lines  still  employ  a  similar  type  of  tower 
as  seen  in  Fig.  i.  It  consists  of  2  channels  with  angle  cross-bracing.  This  type  of 
tower  has  been  installed  at  Tretzo,  in  the  northern  part  of  Italy;  it  is  37  feet  high 


FIG.  5. — Niagara  Crossing.     Water  Edge  Tower,  American  Side. 

above  the  ground,  while  5  feet  is  embedded  into  a  concrete  block.   The  average  spacing 

of  these  towers  is  350  feet,  while  on  this  particular  line,  the  long  spans  are  600  feet. 

Syracuse  Tower.    Fig.  4  shows  a  section  of  the  6o,ooo-volt  transmission  line  tower 

of  the  Syracuse  Rapid  Transit  Company,  New  York,1  along  the  Erie  Canal.     The 


1  The  60,000- Volt  Substation  and  Transmission  Line  of  the  Syracuse  Rapid  Transit  Company. 
Railway  Journal,  July  14,  1906. 


Street 


242 


HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 


FIG.  6. — Dead  End  Towers  at  the  Rochester  Substation.    Niagara,  Lockport  and  Ontario 
Power  Co.    Designed  to  Resist  a  Total  Pull  of  1 1 ,000  Ibs.  per  Cable.    Archbold-Brady  Co. 

route  of  the  line  is  within  the  limits  of  the  city  of  Syracuse;  and  the  towers,  which 
were  built  by  the  Archbold-Brady  Company,  Syracuse,  are  from  45  to  63  feet  high, 
measured  from  the  ground  to  the  top  of  the  bottom  insulator,  and  are  spaced  on  the 
average,  240  feet;  the  longest  span  is  407  feet.     The  conductors  consist  of  seven 
strand  seven-sixteenths-inch  plow  steel  cable. 

In  designing  the  line,  the  assumed  wind  load  was  taken  as  1.25  pounds  per  lineal 
foot  of  cable.     This  estimate  was  based  on  a  wind  pressure  of  30  pounds  per  foot 


ELECTRICAL  TRANSMISSION.  243 

on  a  flat  surface,  or  15  pounds  on  a  round  surface.  The  dead-end  towers  were 
designed  also  for  endwise  strains  under  maximum  wind  and  sleet  loads,  and  calcu- 
lating these  strains,  a  sag  not  exceeding  one-twentieth  of  the  span  was  allowed. 
The  minimum  sag  allowed  was  i  foot  in  40  feet.  The  heights  of  towers  were 
arranged  to  provide  ample  clearance  over  buildings  and  wires.  The  towers  at  the 
angles  were  designed  to  provide  for  side  strains  due  to  the  tension  in  the  cables  based 
on  the  sags  started,  and  also  for  the  pressure  of  the  wind  on  the  cable  and  on  the 
tower.  Enough  insulators  were  provided  at  the  angle  towers  so  that  the  cable  does 
not  make  any  angle  of  over  8i  degrees  on  any  one  insulator.  Where  possible,  the 
cable  was  slacked  off  on  spans  adjacent  to  angles  of  over  3  degrees.  The  towers  at 
angles  and  dead-ends  are  stiff  structures  designed  to  provide  for  the  greatest  assumed 
strains.  In  towers  of  greater  height,  the  section  of  upright  members  in  lower 
panels  was  increased.  The  cross-arms  of  all  towers  were  designed  to  resist  torsional 
strains  due  to  the  pull  of  the  cable  on  the  tops  of  insulators.  The  maximum  pull 
allowable  with  assumed  unit  strains  on  a  single  cross-arm  tower  was  1000  pounds 
for  each  cable.  The  cross-arms  of  towers  at  dead-ends  carry  three  insulators  for 
each  cable,  and  are  designed  to  resist  the  maximum  calculated  pull  due  to  the 
assumed  conditions  of  load  and  sag.  Bolted  joints  in  the  main  members  of  towers  were 
designed  on  the  basis  of  10,000  pounds  shearing  per  square  inch  and  20,000  pounds 
bearing  per  square  inch. 

The  following  are  the  chief  features  of  the  towers:  The  towers  are  of  the  four- 
leg  type  and  are  built  up  of  angles.  The  members  of  the  upper  section  are  laced 
and  riveted  together,  and  the  horizontal  members  throughout  are  riveted  to  the 
upright  members.  The  diagonal  rod  members  are  adjustable  by  right  and  left 
threads  and  devices  at  the  ends.  The  cross-arms  are  specially  designed  and  braced 
to  resist  possible  torsion  should  one  or  all  of  the  cables  break.  All  metal  is  one-fourth 
inch  thick  or  more.  Towers  57  feet  high  and  over  are  supported  on  concrete  piers. 
Each  leg  of  the  tower  is  anchored  by  two  i-inch  bolts  running  to  the  footings.  The 
footing  under  each  pier  is  5  feet  by  3  feet  by  12  inches  thick,  reinforced  to  resist  uplift. 

Oneida  Tower.  Towers  similar  to  these  have  been  installed  by  the  Oneida  Rail- 
road Company,  for  its  electrification  work.  The  standard  height  is  39  feet,  while 
special  towers  run  up  as  high  as  69  feet  from  the  ground  to  the  top  of  the  bottom 
insulator.  The  average  span  is  480  feet  long.  For  the  following  specifications  of 
this  transmission  line,  the  writer  is  indebted  to  the  designers  and  constructors, 
Archbold-Brady  Company,  Syracuse,  N.Y. 

SPECIFICATIONS 

FOR  HIGH-TENSION  LINE  CONSTRUCTION  FOR  THE  ONEIDA  RAILWAY 
COMPANY,   BETWEEN  CLARK'S  MILLS  AND   MANLIUS  CENTER,   N.  Y. 

This  specification  is  intended  to  cover  the  construction  of  a  6o,ooo-volt  transmission  line  along  the 
north  side  of  the  West  Shore  right  of  way  between  the  substations  of  the  Oneida  Railway  Company  at 
Clark's  Mills  and  Manlius  Center,  N.Y. 

>     The  conductors  will  be  of  No.  o  stranded  copper  supported  upon  structural  steel  towers  with 
concrete  foundations. 


244  HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 

TOWERS.  —  The  towers  will  be  of  structural  steel,  as  per  blue  prints  herewith,  and  will  be  designed 
to  sustain  the  assumed  loads  as  follows: 

The  side  pressure  of  the  wind  will  be  taken  at  ij  pounds  per  lineal  foot  of  cable  based  on  a  wind 
pressure  of  30  pounds  per  square  foot  on  a  flat  surface  or  15  pounds  per  foot  on  a  round  surface,  acting 
upon  a  cable  covered  with  a  thickness  of  sleet  equal  to  its  own  diameter. 

The  heights  of  towers  will  be  arranged  to  provide  a  minimum  clearance  of  10  feet  over  buildings 
and  such  wires  as  may  be  crossed  by  this  line. 

Towers  at  angles  will  be  designed  to  provide  for  side  strains  due  to  the  tension  of  the  cable  itself 
and  for  the  pressure  of  the  wind  on  the  cables  and  on  the  tower.  Enough  insulators  will  be  provided 
at  the  angle  towers  so  that  the  cable  will  not  make  an  angle  of  over  7^  degrees  on  any  one  insulator. 
The  wind  pressure  on  the  tower  itself  will  be  assumed  at  60  pounds  per  panel  on  each  half  of  tower. 

UNIT  STRAINS.  —  The  section  of  members  in  the  tower  will  be  calculated  for  a  unit  strain  of  24,000 
pounds  per  square  inch  due  to  the  combination  of  loads  stated  above.  The  strains  in  compression  will 
be  based  on  the  formula, 

24,000  —  96  — . 

DESIGN.  —  The  design  of  towers  in  general  will  be  as  per  drawing  of  45-foot  tower  herewith.  In 
towers  of  greater  heights,  sections  of  upright  members  in  lower  panels  will  be  increased.  The  cross- 
arms  of  all  towers  will  be  designed  to  resist  torsional  strains  due  to  the  pull  of  the  cable  on  the  tops 
of  insulators.  The  maximum  pull  allowable  on  a  single  cross-arm  tower  will  be  1000  pounds  for  each 
cable,  the  ties  being  designed  to  break  at  this  tension.  The  cross-arms  of  towers  at  dead-ends  will 
carry  three  insulators  for  each  cable  and  will  be  designed  to  resist  the  maximum  calculated  pull  due  to 
the  assumed  conditions  of  load  and  sag.  Bolted  joints  in  the  main  members  of  towers  will  be  designed 
on  the  basis  of  10,000  pounds  shearing  per  square  inch  and  20,000  pounds  bearing  per  square  inch. 

FOUNDATIONS.  —  Foundations  of  all  towers  will  be  as  per  drawing  herewith.  For  towers  below 
57  feet  high,  the  legs  of  tower  will  be  extended  into  the  ground  to  a  concrete  footing  about  3  by  7  feet 
reinforced  at  top  and  bottom  as  per  drawing.  The  metal  below  the  surface  of  the  ground  will  be  pro- 
tected by  a  6-inch  concrete  sleeve  run  in  sheet-metal  form  and  extended  slightly  above  the  ground  sur- 
face. In  wet  places  this  protection  will  be  carried  above  the  surface  of  the  ground,  and  the  portion  of 
corner  posts  below  the  splice  angle  will  be  lengthened  in  proportion. 

Foundations  of  towers  57  feet  high  and  over  will  be  concrete  piers  as  per  drawing.  Each  leg  of  the 
tower  will  be  anchored  by  two  one-inch  bolts  running  to  footings.  The  concrete  will  be  proportioned 
one  part  cement,  three  parts  sand  and  five  parts  broken  stone,  or  may  be  one  to  six  cement  and  clean 
sharp  gravel.  The  footing  under  each  pier  will  be  5  feet  by  3  feet  by  10  inches  thick  reinforced  at 
top  and  bottom.  Where  the  ground  is  firm,  no  forms  will  be  used  around  footings.  The  concrete  for 
piers  will  be  placed  in  forms  of  planed  lumber.  All  piers  must  be  carefully  leveled  up  with  neat  cement 
at  the  top,  this  cement  to  be  put  on  before  the  forms  are  stripped.  The  foundation  bolts  will  be  set 
with  wooden  templates  and  to  elevation  shown  on  working  drawings. 

STEPS.  —  Steps  about  20-inch  centers  will  be  provided  for  each  tower  extending  from  first  panel  to 
cross-arm. 

CONSTRUCTION.  —  The  towers  will  be  riveted  in  the  shop  as  far  as  practicable.  The  field  con- 
nections may  be  bolted.  The  bolts  in  the  two  lower  panels  will  be  upset. 

PINS.  —  The  pins  will  be  of  malleable  iron  18  inches  high  above  cross-arm  and  designed  to  with- 
stand a  strain  of  2000  pounds  in  any  direction  applied  to  the  insulator.  They  will  be  attached  to  the 
tower  with  four  f -inch  bolts. 

DEAD-END  AND  SPECIAL  STRUCTURES.  —  Where  the  line  is  dead-ended  or  where  special  structures 
are  required  at  the  sub-stations  a  separate  agreement  will  be  made,  these  structures  not  being  included 
in  this  contract.  ,-• 

HANDLING  AND  STRINGING  CABLES.  —  The  cable  will  be  delivered  to  the  contractor  at  convenient 
freight  stations  along  the  line.  The  contractor  will  string  same  upon  the  towers,  using  great  care  that 
the  cable  is  not  kinked  or  damaged  during  the  operation.  The  cable  will  be  strung  in  general  with  a 


ELECTRICAL  TRANSMISSION. 


245 


,;•-  — 


Malleable  Iron 
;6»x5"YeJtoHrPine 


&'x5' 'Yellow  Pine.. 

Dressed 


6'*y  'Timb 
to  5%'x 


i2-foot  sag  on  48o-foot  span  at  32°  F,,  which  corresponds  to  a  normal  tension  of  300  pounds  in  the 
cable.  Allowance  will  be  made  for  temperature  so  that  the  cable  will  have  a  sag  of  12  feet  at  32°  F. 
Where  the  spans  vary,  the  sag  will  be  proportioned  so  that  the  normal  tension  in  the  cable  will  remain 
practically  the  same. 

The  cable  will  be  tied  in  with  wire  furnished  by  the  company,  the  form  of  tie  to  be  agreed  upon  later, 
but  these  ties  will  have,  as  near  as  practicable,  a  breaking  strength  of  1000  pounds.  On  the  double 
cross-arm  equalizing  saddles  will  be  provided  to  insure  equal  strains  being  brought  upon  the  insulators. 
At  the  dead-end  towers,  clamps  will  be  arranged  for 
holding  the  ends  of  the  cable  securely.  Saddles  will  be 
designed  to  facilitate  removing  of  a  defective  insulator. 

CHARACTER  OF  WORK.  —  All  work  in  shop  and  field 
must  be  carefully  and  accurately  done,  and  the  struc- 
tures left  complete  and  finished  according  to  the  best 
practice  in  this  class  of  work. 

PAINT.  —  All  work  to  have  one  shop  coat  of  red 
lead  and  oil  and  one  coat  in  field  of  graphite  paint  of 
approved  manufacture.  All  work  to  be  done  accord- 
ing to  the  directions  of  the  Engineer  of  the  Oneida 
Railway  Company. 


New  York  Central  Tower.  A  steel  tower 
of  lattice  construction  for  carrying  a  number 
of  conductors  on  wooden  cross-arms,  as  in- 
stalled in  connection  with  the  New  York  Cen- 
tral and  Hudson  River  Railroad,  is  seen  in 
Fig.  y.1  "The  component  parts  of  the  tower 
consist  of  the  following:  Four  L's  3  inches 
by  3  inches  by  five-sixteenths  inch;  lacing, 
one  L  2\  inches  by  i^  inches  by  three-six- 
teenths inch  (single)  ;  connecting  L's  2\  inches 
by  z\  by  one-fourth  inch;  cap  plate  of  malle- 
able iron;  rivets  three-fourths  inch  in  dia- 
meter. The  estimated  quantities  of  material 
for  one  pole  are:  steel,  1340  pounds;  concrete, 
6.5  cubic  yards;  timber,  71  feet  board 
measure. 

The  general  conditions  in  installing  the 
lines  were  as  follows:  Distance  from  the 
center  to  center  of  poles  on  tangents  is  150 
feet,  sag  30  inches;  distance  on  i-degree 


§.  Section  A-A 


l*4  Concrete 

*%** 


. 


Top  of  Foundation  6'ottove 
Base  of  Rail  in  Cut 
\  lop  of  Foundation  6' 
I  below  Base  of  Rail  on  nil. 


-I'  | 

Concrete   I 
i'4-?r 


-  No.3  Annealed  Solid 
Wire  Connection  to 


Elevation.. 


FIG.  7. — Standard  Steel  Tower  of  the 
New  York  Central  Railroad. 


curve  is  141  feet,  sag  27  inches;  on  2-degree  curve,  133  feet,  sag  24  inches;  on 
3-degree  curve,  125  feet,  sag  21  inches;  on  4-degree  curve,  118  feet,  sag  18^  inches; 
on  5-degree  curve,  112  feet,  sag  16^  inches;  on  6-degree  curve,  107  feet,  sag  15 
inches.  The  sag  of  wires  for  all  spans  is  computed  at  70°  F.  with  no  wind.  Load 
on  poles:  Six-wire  circuit  No.  i,  each  0.728  inch  diameter,  area  400,000  C.M.,  weight 


1  Two  Forms  of  Transmission  Towers  in  New  York  State.     Street  Railway  Journal,  July  14,  1906. 


ELECTRICAL  TRANSMISSION. 


A.E.&M 

247 

UNIV.  OF  C 


-yo 

'M 

i 

! 

•  •  f 

i  i>! 

;  i 

ii 

li 

i 

Iji 

« 

• 

i|| 

i 

if 

. 

li 

.  T 

1  1 

||' 

if! 

i 

!' 

'    A 

t    1 

i  1 

J 

II 

u 

ft 

1  1, 

4-1 

I  i 

i 
i  \ 
i 

K 

9—  .,--- 

' 

FIG.  1 1 . — Type  of  Tower  used  in  5o,ooo-volt  Italian  Transmission  System. 

1.22  pounds  per  linear  foot;  four-wire  circuit  No.  2,  one-fifth  inch  diameter,  area 
1,000,000  cm.,  weight  3.55  pounds  per  linear  foot;  three  wires,  circuit  No.  3,  each 
0.165  inch  diameter,  area  27,225  cm.,  weight  .074  pound  per  linear  foot,  together 
with  one-half  inch  coating  of  ice  on  all  wires.  The  wind  pressure  is  30  pounds  per 
square  foot  on  the  surface  of  the  pole,  and  on  all  wires  covered  with  one-half  inch 
coating  of  ice.  Unit  stresses:  Tension,  30,000  pounds  per  square  inch  net  section; 

30,000  pounds 

L2 

I  = 


125  r3 

the  compression  is  per  square  inch  cross  section;  shear  on  rivets  22,500  per  square 
inch;  bearing  on  rivets,  45,000  pounds  per  square  inch;  maximum  bending  moment  on 
pole,  2,910,000  inch-pounds;  maximum  overturning  moment  of  pole,  3,340,000  inch- 


248 


HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 


pounds.  The  painting  is  one  coat  of  New  York  Central  standard  red  lead  paint  on 
each  surface  in  contact  before  assembling,  and  one  coat  on  the  entire  pole  before 
leaving  the  shop.  Before  erection  two  heavy  coats  of  New  York  Central  asphaltum 
varnish  are  added." 

Luzerne  Tower.  A  type  of  recent  Swiss  transmission  line  construction  is  given  in 
Fig.  9,  and  is  used  in  connection  with  the  27,ooo-volt  line  at  Luzerne,  Switzerland.1 
The  towers  are  about  45  feet  high  measured  from  the  ground  up  to  the  lower  insulator. 
As  will  be  seen  in  detail,  Fig.  10,  the  insulators  are  mounted  on  vertical  oak  members 
carried  by  transverse  channels  and  are  3.3  feet  apart  on  the  leg.  The  insulators  are 
fastened  to  galvanized  iron  pins  by  hemp,  linseed  oil,  and  shellac.  To  prevent  a  line 
from  dropping  to  the  ground,  guard  angles  are  provided.  Owing  to  adverse  con- 
ditions, several  of  the  towers  had  to  be  placed  on  a  cantilever  construction  overhanging 
the  lake  as  seen  in  Fig.  9. 

For  this  purpose  a  cantilever  structure  had  to  be  embedded  in  a  heavy  concrete 
block,  in  order  to  protect  the  cantilever  and  the  tower  from  boulders  coming  down 
the  mountain  slope;  heavy  masonry  abutments  were  placed  on  top  of  the  concrete 
block;  a  passageway  is  provided  to  reach  the  tower.  The  total  length  of  the  canti- 
lever is  about  30  feet.  The  spacing  of  the  cantilever  poles  is  400  feet,  while  the  normal 
spacing  for  the  land  towers  is  about  200  feet. 


FIG.  12. — Highway  and  Telephone  Crossing  for  5o,ooo-volt  Line  Near  Lecco,  Italy;  also 

Section  Switch  House. 


Brusio  Tower.   The  latest  and  most  prominent  transmission  line  is  that  of  the 
Brusio   Plant,   Switzerland,  transmitting  50,000  volts  for  some  88.5   miles  in  the 

1  The  27,000- Volt  Transmission  System  of  the  Obermatt  Power  Plant,  Switzerland.    Electrical  Review, 
June  13,  1908. 


ELECTRICAL  TRANSMISSION. 


249 


northern  part  of  Italy.     Duplicate  parallel  lines  (13  to  16.5  feet  apart)  run  the  entire 
length  of  the  line.     As  they  run  over  mountains  and  valleys  of  great  variation  in 
altitude,  and  owing  to  great  difference  in 
temperatures,  frequent  storms  and  atmos- 
pheric discharges,  the  peaks  of  the  moun- 
tains were  avoided. 

The  standard  tower  (see  Fig.  n)  is  of 
angle  iron  lattice  construction,  and  has 
brackets  to  accommodate  two  3-phase 
circuits.  Each  cable  consists  of  nineteen 
2.6  mm.  copper  wires,  the  total  diameter 
being  14  mm.  (about  0.5  inch).  The 
insulators  are  of  the  two-petticoat  type,  and 
are,  according  to  Swiss  practice,  mounted 
on  wood,  carried  on  steel  brackets.  The 
tower  is  about  40  feet  high  from  the  ground 
to  the  lowest  insulator,  and  spaced  on  the 
average,  393  feet;  the  longest  span  being 
1280  feet,  for  which  special  towers  were 
employed.  All  towers  are  set  in  concrete, 
and  designed  for.  a  wind  pressure  of  70 
miles  an  hour,  allowing  a  stress  of  17,000 
pounds;  the  stress  of  the  copper  cables  is 
8500  pounds  per  square  inch,  accommo- 
dating a  temperature  change  of  120°  F. 

Of  the  3100  towers  erected,  there  are 
only  four  different  types  employed,  weigh- 
ing from  1250  to  2500  pounds,  and  cost  on 
the  average,  $80  each,  including  founda- 
tion and  erection.  The  insulators  cost 
$2.60  each,  including  mounting  and  the 
wooden  blocks.  At  present,  each  line 
carries  only  one  circuit,  amounting  to  900  FIG.  13. — Aermotor  Towers.  At  the  Right  a 
gross  tons  of  copper;  the  laying  of  same  Medium  Weight  Tower  for  Suspended  Insu- 
...  .  i  lators  for  the  no,ooo-volt  Transmission 

cost  $28  per  mile  of  transmission.  System  of  the   Grand  Rapids-Muskegon 

Suspended   Insulator    Towers.    All    the        Power  Co.,  Mich, 
above-discussed  towers  are  for  pin  insula- 
tors; the  suspended  type  of  insulators  requires  a  change  in  the  brackets  of  trans- 
mission towers.1     Types  of  such  towers  have  been  constructed  by  the  Aermotor 
Company  for  the  Grand  Rapids-Muskegon  Power  Company;2  they  are  from  40  to 

1  Some  New  Methods  in  High  Tension  Line  Construction,  by  H.  W.  Buck.    Am.  Inst.  of  E.  E.,  June, 
1907. 

2  The  100,000- Volt  Steel  Tower  Line  of  the  Grand  Rapids-Muskegon  Power  Company.      Electrical 
World,  Nov.  2,  1907. 


250 


HYDROELECTRIC  DEVELOPMENTS  AND  ENGINEERING. 


60  feet  high  and  spaced  about  500  feet  apart.     Each  leg  is  anchored  to  a  3-inch  angle 
7  feet  10  inches  long,  set  in  concrete  to  prevent  corrosion,  except  for  about  10  inches 

at  the  bottom,  which  is  left  bare  to  pro- 
vide an  effective  ground.  Stranded  copper 
cables  with  hemp  centers,  and  having  a  con- 
ductivity equal  to  No.  2  solid  wire,  are  sus- 
pended from  brackets  by  means  of  5  disk 
link  insulators.  The  steel  angles,  to  which 
the  links  of  the  towers  are  anchored,  were  set 
in  concrete  at  a  mixing  plant  at  one  end  of 
the  line  and  afterwards  transported  to  the 
points  needed.  Each  complete  anchor  weighs 
about  275  pounds.  The  concrete  envelope  is 
elliptical  in  section,  the  axes  of  the  ellipse 
being  4.5  inches  and  6  inches  respectively. 
One  3-inch  4-pound  steel  channel  and  several 
short  reinforcing  rods  were  fastened  horizon- 
tally near  the  bottom  of  each  main  angle  as 
anchors.  These  channels  and  rods  also  were 
set  in  concrete  disks,  sheet-iron  molds  being 
used  for  the  purpose. 

Economical  Spans.  In  laying  out  a  trans- 
mission line  it  is  of  foremost  importance 
first,  to  find  out  the  most  economical  span, 
that  is,  after  the  size  of  the  conductors  has 
been  calculated,  not  omitting  the  line  loss; 
the  next  step  is  to  ascertain  the  proper  spac- 
ing. Having  determined  from  the  foregoing 
chapter  the  necessary  cross  section  of  copper 
conductor,  the  choice  of  material,  whether 


FIG.  14. — Type  of  Tower  for  Suspended 
Insulator,  Southern  Power  Co.,  Char- 
lotte, N.  C. 


copper,  aluminum,  or  steel  conductors  should  be  used,  must  be  decided. 

TABLE    I. —  TENSILE    STRENGTH    AND    CONDUCTIVITY    OF    CONDUCTORS. 


Material. 

Tensile  strength, 
pounds  per  square 
inch. 

Conductivity. 

Copper  
Aluminum  

55.°°° 

28,000 

100 
62 

Steel  .  . 

IOO,OOO 

12 

In  the  foregoing  table  the  conductivities  and  tensile  strengths  of  conductors  for 
high  tension  transmission  lines  are  given;  in  connection  with  same  the  market  price 
of  the  materials  must  be  considered,  especially  those  of  copper  and  aluminum  which 
vary  greatly.  From  this  and  in  conjunction  with  the  design  of  the  tower  the  most 
economical  span  can  only  be  determined  by  making  comparative  estimates. 


ELECTRICAL  TRANSMISSION.  251 

Line  Stresses.  The  following  example,  by  B.  Wiley,  illustrates  a  method  for 
calculating  the  stresses  on  steel  towers.1  This  problem  was  worked  out  for  a  span 
at  the  Homestead  Steel  Works,  Pennsylvania,  to  cross  the  Monongahela  River. 
The  dimensions  and  other  data  are  given  in  the  illustration  and  calculations. 

The  conditions  that  form  the  basis  of  the  calculations  are  as  follows:  Line 
voltage,  250;  load  to  be  carried,  800  amperes;  drop  of  voltage  permissible,  40  volts; 
necessary  size  of  copper  conductor,  1,000,000  circular  mils;  necessary  size  of  alumi- 
num conductor,  1,600,000  circular  mils  (duplicate  lines  of  800,000  circular  mil 
cable  were  used  for  convenience  of  construction) ;  maximum  sag  allowable  at  212°  F., 
35  feet;  maximum  wind  probable  pressure,  40  pounds  per  square  foot;  minimum 
temperature,  20°  F.;  probable  ice  coating,  one-fourth  inch  thick.  The  tensile 
strength  of  hard  drawn  aluminum  wire  is  35,000  pounds  per  square  inch;  its  conduc- 
tivity, 63,  as  compared  with  copper  at  100;  and  the  coefficient  of  expansion,  .0000231 
per  degree  Fahrenheit. 

When  a  wire  is  suspended  between  two  supports  it  takes  a  curve  known  tech- 
nically as  the  catenary.  In  the  case  at  hand  the  catenary  comes  very  close  to  the 
parabola,  which  gives  the  following  relations: 

T  =— . 
Bd 

where  T  =  tension  in  cable  at  ends, 

L  =  length  of  span  in  feet, 

w  =  weight  per  foot  of  wire, 

d  =  the  central  deflection  in  feet. 

Obviously  T  will  be  a  maximum  when  w  is  at  its  maximum  and  d  at  its  mini- 
mum. The  wire  will  have  its  greatest  weight  per  foot  when  coated  with  ice  and  is 
withstanding  a  heavy  wind  pressure;  and  the  deflection  will  vary  directly  as  the 
temperature. 

The  weight  of  i  foot  of  8oo,ooo-centimeter  Ai  cable  =     .736  pound 

The  weight  of  one-fourth  inch  ice  coating  per  foot      =    .389  pound 
Total  weight  per  foot  =  1.125  pounds 

Taking  the  wind  pressure  at  40  pounds  per  square  foot  and  as  acting  on  the  cross- 
section  of  ice  covered  wire,  the  pressure  per  foot  is  4.166  pounds.  As  this  force 
acts  at  right  angles  to  the  weight,  the  resultant  force  =  Vi.i252  +  4-i662  =  4.31 
pounds,  which  may  be  considered  the  maximum  for  w. 

Sd2 
For  the  catenary  curve,  L'  =  L  -\ , 

where  L'  =  actual  length  of  cable, 

L    =  length  of  span, 
d   =  central  deflection. 

t  /3  L  (L'  -  L) 
Transposing,  d   =  y  -       

1  A  Long  Span  Transmission  Line,  by  B.  Wiley.     Electrical  World  and  Engineer,  April  16,  1904. 


252 


HYDROELECTRIC  DEVELOPMENTS  AND  ENGINEERING. 


From  these  two  formulae  d  can  be  figured  for  any  temperature,  the  initial  sag 
being  35  feet  at  212°  F.  The  following  table  gives  the  sag  for  temperatures  between 
212°  F.  and  minus  20°  F.: 

TABLE    II. —  SAG    AT    DIFFERENT    TEMPERATURES. 


Temperature, 
degrees  F. 

Deflection,  feet. 

Temperature, 
degrees  F. 

Deflection,  feet. 

212 

35  -o 

90 

27.1 

2OO 

34-7 

80 

26.  4 

IQO 

33-8 

70 

25.6 

180 

33-2 

60 

24.9 

170 

32  5 

5° 

24.1 

160 

31.8 

40 

23-3 

15° 

31.2 

3° 

22.  5 

140 

3°-5 

20 

21-7 

130 

29.9 

10 

2O-9 

1  20 

29.  2 

O 

2O.  I 

no 

28  5 

—  2G 

19.  2 

100 

27.8 

—  2O 

183 

Substituting  in  equation  (i)  the  values 


w  =4.31  pounds  (the  maximum  weight), 
d  =  18.3  feet  (minimum  deflection), 
L  =  iooo  feet, 


T  (the  maximum  tension)  = 


iooo2  X  4.31 
8  X  18.3 


=  29,400  pounds. 


The  sectional  area  of  8oo,ooo-C.M.  cable  is  .8  square  inch,  giving  a  tensile  strength 
of  .8  X  35,000  =  28,000  pounds  per  cable. 

Comparing  this  result  with  the  maximum  tension,  29,400  pounds,  it  is  seen  that 
the  line  will  not  stand  the  severe  conditions  as  set  down.  To  relieve  the  strain,  the 
line  should  be  lengthened  in  the  fall  and,  to  prevent  excessive  sag,  taken  up  again 
in  the  spring. 

Suppose  a  range  of  temperature  from  60°  F.  to  —  20°  F.  be  taken  for  the  winter. 
Then  the  line  could  be  allowed  a  drop  of  35  feet  at  this  maximum  temperature,  which, 
by  reference  to  the  table,  would  make  the  equivalent  sag  at  —  20°  F.  28.4  feet. 

Substituting  in  formula  (i), 


T  = 


iooo2  X  4.31 
8  X  28.4 


=  19.000  pounds, 


or  the  one  setting  would  give  a  safe  tension  on  the  cable  for  the  conditions  noted, 
though  for  severe  conditions  it  would  be  well  to  give  the  maximum  drop  of  35  feet, 
as  the  adjustment  requires  only  a  few  minutes'  work. 

As  an  example,  the  maximum  strain  per  cable  is  19,000  pounds,  or  per  tower, 
4  X  19,000  =  76,000  pounds.  The  horizontal  component  due  to  the  wind  pressure 
is  transmitted  to  the  foundations  and  the  direct  pull  to  the  steel  brace  rods  behind. 


ELECTRICAL  TRANSMISSION. 


253 


TRANSMISSION    LINE   TOWERS   AND    ECONOMICAL    SPANS.1 

For  any  given  transmission  line  there  is  a  certain  length  of  span  which  is  most 
economical.  A  determination  of  what  the  economical  span  is,  in  any  case,  can  only 
be  made  by  obtaining  data  showing  the  variation  of  each  item  of  cost  which  changes 
with  the  length  of  span.  In  a  steel-tower  line  the  cost  of  the  tower  is  probably  the 
most  important  among  those  items  which  vary  with  the  length  of  span.  As  the  span 
is  made  longer,  the  towers  must  be  made  higher  and  stronger.  The  purpose  of  this 
paper  is  to  describe  a  method  by  which  the  relation  between  the  height,  strength, 
and  cost  of  a  tower  of  given  form  may  be  expressed.  The  application  of  this  method 
to  the  problem  of  fixing  the  economical  span  will  also  be  shown. 


-J« 


FIG.  i. 


FIG.  2. 


A  transmission  tower  has,  in  general,  three  duties  to  perform: 

1.  It  must  have  strength  to  resist  wind  pressure  on  its  various  members. 

2.  It  must  have  strength  to  withstand  certain  external  loads  due  to  cables, 
guys,  etc. 

3.  It  must  have  strength  to  sustain  its  own  weight. 

The  weight  of  a  given  transmission  tower  may  therefore  be  considered  to  be  made 
up  of  three  components,  each  component  corresponding  to  one  of  these  sources  of 
stress.  The  following  equation  may  then  be  written  for  the  weight  of  the  structure 
shown  in  diagram  in  Fig.  i, 

W  =  Ww  +  W,  +  W5  (i) 

in  which  W  =  total  weight. 

1  A  paper  by  D.  R.  Scholes.     Am.  Inst.  of  E.  E.,  Niagara  Falls,  N.Y.,  June  26,  1907. 


254  HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 

TFW  =  weight  necessary  to  provide  strength  against  wind  pressure. 
WL  =  weight  necessary  to  provide  strength  against  external  loads. 
Ws  =  weight  necessary  to  enable  the  structure  to  sustain  its  own  weight. 

Assume  that  the  structure  shown  in  Fig.  i  has  been  designed  for  a  certain  wind 
pressure,  and  for  certain  external  loads  of  given  amount  and  manner  of  application. 
Each  member  in  the  structure  may  be  considered  to  involve  three  components  of 
thickness,  each  component  corresponding  to  one  of  the  three  general  sources  of  stress. 
In  determining  the  value  of  Ww,  the  stress  in  each  member  resulting  from  wind 
pressure  alone  would  first  be  computed;  with  this  as  a  basis,  the  component  of 
thickness  of  each  member  necessary  to  sustain  the  stress  due  to  wind  pressure  alone 
would  then  be  calculated.  Having  determined  the  component  of  thickness  of  each 
member  corresponding  to  the  stated  wind  pressure,  the  value  of  Ww  would  follow 
directly.  A  similar  method  would  be  used  in  finding  WSL  and  Ws. 

This  method  will,  perhaps,  be  made  more  clear  by  referring  to  Fig.  2,  which 
shows  in  cross  section  one  of  the  members  of  the  tower  of  Fig.  i. 

In  the  figure, 
t  =  total  thickness, 

/w  =  thickness  corresponding  to  wind  pressure, 
/L  =  thickness  corresponding  to  external  loads, 
ts  =  thickness  corresponding  to  weight  of  structure, 

/sw  =  thickness  corresponding  to  component  Ww  of  the  weight  of  the  structure, 

/SL  =  thickness  corresponding  to  component  W \  of  weight  of  load. 

It  is  seen  that  t  =  tw  +  tL  +  ts  (2) 

and  /  =  /w  +  /t  +  /sw  +  /„.  (3) 

since  /s  =  /sw  +  /SL. 

The  thickness  of  any  other  member  of  the  tower  may  be  considered  to  be  divided 
up  into  parts  in  the  same  manner.  Since  /s  is  divided  into  the  parts  /sw  and  £SL,  a 
corresponding  division  may  be  made  in  the  term  W&  of  equation  (i)  which  gives 

W  =  Ww  +  W,  +  Wsw  +  W^  (4) 

where  TFWS  =  weight  necessary  to  provide  strength   to    sustain  TFW  and  Waw,  and 
WSL  =  weight  necessary  to  provide  strength  to  sustain  WL  and  WSL. 

The  structure  shown  in  diagram  in  Fig.  i  involves  members  of  three  general 
kinds;  namely,  beams,  struts,  and  tension  members. 

The  bending  moment  produced  in  a  given  beam  by  a  given  load  W  may  be 
expressed  by  the  equation 

M  =  CWl,  (5) 

M  =  maximum  bending  moment, 
/  =  distance  between  supports, 

C  —  constant,  dependent  on  the  manner  in  which  the  load  is  distributed.  The 
relation  between  the  bending  moment  and  the  stress  in  the  most  remote  fiber  of  the 
beam  is  given  by  the  equation  p/?p 

Jf-— ,  (6) 


ELECTRICAL  TRANSMISSION.  255 


M  =  bending  moment, 

P  =  stress  per  unit  area  in  most  remote  fiber  of  beam, 
F  =  cross-sectional  area  of  beam, 
k  =  radius  of  gyration  of  beam  section, 
e  =  distance  of  most  remote  fiber  from  neutral  axis. 

Combining  these  two  expressions,  the  equation 


Cle 

is  obtained,  which  gives  the  load  which  the  beam  will  carry,  P'  being  the  ultimate 
strength  of  the  material  in  the  beam. 

Now  if  k  is  the  radius  of  gyration  of  a  given  figure,  the  radius  of  gyration  of  a 
second  figure  similar  to  the  first  but  of  different  size  is  equal  to  nk,  n  being  the  ratio 
between  corresponding  linear  dimensions  of  the  two  figures. 

If,  therefore,  a  second  beam  be  considered,  exactly  similar  to  the  first,  but  of 
different  size  and  length,  n  being  the  ratio  between  corresponding  linear  dimensions 
of  the  two  beams,  the  load  which  this  second  beam  will  carry  is 

Pn2Fn2k2         2  PFk  W2 

W~  =  -         —  =  n2      —  ,    and  —  -  =  n2.  (8) 

Cnlne  Cle  W 

Expressed  in  words,  this  relation  may  be  stated  as  follows: 

The  load  which  a  beam  of  given  form  will  carry  varies  as  the  square  of  its  linear 
dimensions. 

The  strength  of  a  strut  against  compressive  stress  is  given  by  Rankine's  formula: 

P'  F 

W  =  —  -  (9) 

,  I2 

*  '  . 

W  =  ultimate  strength  of  strut. 
P'  =  ultimate  compressive  strength  of  material. 
F  =  cross-sectional  area. 

I  =  length. 

k  =  radius  of  gyration. 

C  =  constant,  depending  on  kind  of  material. 

And  the  strength  of  another  strut,  exactly  similar  to  the  first  but  of  different 
size  and  length,  n  being  the  ratio  between  corresponding  linear  dimensions  of  the 
two  struts,  is 

P'n2F  P'F  W, 

W.  =  -          -  =  «,  -       also     —  -  =  n2.  (10) 

,  n2l2  P  W 

I+C—  ;  I+C- 

n2k2  k2 

Expressed  in  words,  this  relation  may  be  stated  as  follows: 

The  load  which  a  strut  of  given  form  will  carry*  varies  as  the  square  of  its  linear 
dimensions. 


256 


HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 


The  strength  of  a  tension  member  is  directly  proportional  to  its  cross-sectional 
area;  that  is,  it  varies  as  the  square  of  its  linear  dimensions. 

An  investigation  of  the  action  of  a  member  subjected  to  torsional  loads,  similar 
to  those  just  made  for  beams,  struts,  and  tension  members,  would  show  a  like  rela- 
tion; that  is,  the  load  which  a  member  of  given  form  subjected  to  torsion  will  carry, 
varies  as  the  square  of  its  linear  dimensions.  This  investigation  is  not  undertaken 
here,  however,  because  members  of  this  character  are  little  used  in  transmission 
towers. 

Returning  to  the  structure  shown  roughly  by  Fig.  i.  It  is  usually  assumed  that 
the  actual  pressure  on  any  part  of  such  a  structure,  produced  by  a  wind  of  given 
velocity,  is  directly  proportional  to  the  exposed  area  of  that  part.  Now  the  exposed 
area  of  any  part  is,  in  general,  dependent  on  its  length  and  breadth,  but  not  upon  its 
thickness.  It  therefore  follows  that  if  the  structure  shown  in  Fig.  3  is  geometrically 


FIG.  3. 


FIG.  4. 


similar  to  that  of  Fig.  i,  in  every  respect  except  the  thickness  of  its  parts,  and  is  of 
different  size,  the  ratio  between  corresponding  linear  dimensions  being  n,  the  load 
produced  on  any  part  of  the  second  structure  by  a  wind  of  given  velocity  is  equal  to 
n2  times  the  load  produced  on  the  corresponding  part  of  the  first  structure  by  the  same 
wind.  It  also  follows  that  the  stress  in  any  member  of  the  second  structure  under 
these  conditions,  due  to  wind  pressure,  is  equal  to  n2  times  that  in  the  corresponding 
member  of  the  first  structure. 
For  the  structure  of  Fig.  3, 


W  = 


+W' 


and 


(12) 


ELECTRICAL  TRANSMISSION.  257 

From  the  foregoing  discussion  of  the  relation  between  the  size  and  strength  of 
beams,  struts,  etc.,  of  given  form,  it  is  evident  that 


and  W'w  =  nWw  (14) 

both  structures  being  calculated  for  the  same  wind  pressure. 
Again  referring  to  the  equation  for  beams, 

P'Fk2  WCle 

w=aT>   or  F  =  ^' 

It  is  evident  that  if  k  and  e  can  be  kept  constant,  the  sectional  area  which  a 
given  beam  must  have  to  sustain  a  load  distributed  in  a  given  manner  varies  directly 
as  the  load  and  directly  as  the  length  of  the  beam.  The  sections  commonly  employed 
as  beams  are  angles,  channels,  and  I-sections.  By  reference  to  any  handbook  of 
such  sections  it  will  be  seen  that  for  any  of  these  sections  of  a  given  nominal  size  the 
area  of  the  beam  may  vary  considerably  without  producing  more  than  a  negligible 
change  in  the  value  of  k  or  e. 

Hence,  if  after  the  nominal  size  of  a  beam  has  been  determined,  it  is  desired  to 
vary  either  the  load  or  the  length  of  the  beam,  the  sectional  area  should  be  made  to 
vary  directly  as  the  load  and  directly  as  the  length  of  the  beam. 

From  the  formula  for  columns, 

P'F 


it  is  seen  that,  if  the  ratio  l/k  is  kept  constant,  the  strength  of  the  column  is  directly 
proportional  to  its  cross-sectional  area. 

From  the  nature  of  a  tension  member,  its  strength  is  proportional  to  its  sectional 
area. 

Again  refer  to  Fig.  i.  It  is  assumed  that  this  structure  is  subjected  to  the  loads 
Gp  G2,  G3,  etc.,  these  loads  being  placed  upon  it  through  cables,  guys,  or  the  like. 
The  application  of  each  of  these  loads  will,  in  general,  produce  certain  stresses  in 
each  of  the  members  of  the  structure.  The  stress  in  a  given  member  produced  by  a 
given  load  will  be  directly  proportional  to  the  load,  and  the  magnitude  of  the  stress 
will  depend  on  the  particular  position  which  the  member  occupies.  If  a  certain 
system  of  loads,  as  G,,  G2,  G3,  and  G4,  is  applied  to  the  structure,  the  resultant  stress 
in  any  given  part  may  be  considered  to  be  made  up  of  the  components  .4Gp  BG2, 
CG3,  and  DG4  —  A,  B,  C,  and  D  being  constants.  Also,  if  each  of  the  loads  is  multi- 
plied by  a  factor  r,  the  resultant  stress  in  any  member  will  also  be  multiplied  by  that 
factor. 

Moreover,  if  a  system  of  loads  as  Gp  G2,  G3,  etc.,  be  similarly  applied  to  another 
structure  geometrically  similar  to  that  of  Fig.  i,  but  of  different  size,  the  stress  pro- 


258  HYDROELECTRIC  DEVELOPMENTS  AND  ENGINEERING. 

duced  in  a  given  member  of  the  second  structure  by  these  loads  will  be  equal  to  that 
produced  by  them  in  the  corresponding  member  of  the  first  structure.  In  Other 
words,  the  stress  in  any  member  is  dependent  only  upon  the  geometrical  form  of  the 
structure  and  the  amount  and  manner  of  application  of  the  loads  producing  it;  and 
is  not  affected  by  the  actual  size  of  the  structure. 

Let  the  structure  indicated  in  Fig.  4  be  geometrically  similar  to  that  of  Fig.  i 
in  all  respects  except  the  thickness  of  its  members.  Let  the  system  of  loads,  rG}, 
rG2,  rG3,  and  rG4,  applied  to  this  structure  be  similar  to  that  applied  to  the  structure 
of  Fig.  i,  but  of  different  magnitude,  the  ratio  between  corresponding  loads  being  r. 
Also  let  the  structure  of  Fig.  4  be  designed  for  a  different  wind  pressure  from  that 
of  Fig.  i,  the  ratio  between  the  wind  pressures  per  unit  area  in  the  two  cases  being  p. 

For  the  structure  of  Fig.  4, 

W"  =  W\  +  W'\  +  W"sw  +  W"SL  (17) 

v  =  <"w  + 1\  +  <"sw  +  rSL  (18) 

In  view  of  the  relations  pointed  out  between  the  length,  sectional  area,  and 
strength  of  the  various  kinds  of  members  involved  in  the  structures,  it  follows  that 

(19) 
(20) 

+ (21) 

JP'SL=nWaL+.  ...  (22) 

To  make  equations  (21)  and  (22)  strictly  accurate,  terms  must  be  added  to 
represent  the  weight  added  to  provide  for  the  strength  necessary  to  take  care  of  each 
individual  increment  of  weight.  This  will  involve  a  convergent  infinite  series  in  each 
case.  All  terms  of  these  series,  except  the  first,  are,  however,  relatively  unimpor- 
tant and  will  therefore  be  neglected. 

Substituting  in  equation  (17) 

W"  =  n*pWw  +  nrW^  +  n*pWsvl  +  »WSL.  (23) 

This  is  a  general  equation,  and,  given  the  values  of  TFW,  WL,  Wsvf  and  PFSL  for 
the  structure  of  Fig.  i,  it  makes  it  possible  to  calculate  the  weight  of  the  structure  of 
Fig.  4  without  going  through  the  routine  of  calculating  the  stresses  in  each  member 
and  the  sizes  and  weights  of  the  parts  necessary  to  carry  these  stresses. 

The  application  of  this  formula  to  the  problem  of  fixing  the  economical  span 
for  a  given  transmission  line  is  obvious.  A  tower  for  a  given  length  of  span  would 
be  designed  to  furnish  the  strengths  necessary  for  that  span.  The  design  would  be 
made  in  accordance  with  the  manufacturing  facilities  available  for  producing  the 
structures.  The  stresses  in  each  member  would  be  carefully  calculated  and  the  val- 
ues of  TFW,  WL,  Wsw  and  TFSL  found  for  the  structure.  Having  found  these  values, 
the  weight  of  any  similar  structure  for  any  length  of  span  could  be  determined  by 
substitution  in  equation  (23). 

It  is  to  be  observed  that  this  method  of  treating  the  case  assumes  that  both  wind 


ELECTRICAL  TRANSMISSION. 


259 


loads  and  external  loads  are  to  be  applied  to  the  structure  simultaneously.  This  is 
usually  the  case.  In  other  cases,  however,  the  method  to  be  pursued  wpuld  be 
similar,  but  modified  to  suit  the  peculiarities  of  the  case. 


t 

3 

\ 

\ 

I 

4 

\ 

x 

x. 

*> 

L^ 

•~—  -. 

9         i         3.         )        4 

r          6          7         £          9         10        II         it        13        14        4 

WIDTH  or  DAH  ///  /r/A 

FIG.  6. 

It  is  also  to  be  borne  in  mind  that  formula  (23)  contemplates  that  variations  in 
the  cross  section  of  any  member  will  be  made  in  such  manner  that  the  radius  of 
gyration  of  the  section  will  be  kept  proportional  to  n  in  every  case,  and  also  that  no 
appreciable  variation  from  geometric  similarity  will  occur.  These  assumptions 
do  not  involve  any  appreciable  inaccuracy  within  the  range  of  ordinary  practice. 


260  HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 

Before  the  problem  of  providing  steel  towers  for  supporting  the  cables  of  a  given 
transmission  line  can  be  considered,  the  general  features  of  the  line,  its  voltage, 
size  of  conductor,  etc.,  must  be  fixed.  To  show  the  application  of  the  formula 
just  developed,  the  following  set  of  general  assumptions  has  been  selected  as  a 
working  basis,  and  it  is  believed  that  they  are  in  accord  with  average  high-grade 
practice. 

General  Assumptions.     System:  three-phase  alternating  current. 

Conductor:  400,000  circular  mils  stranded  copper.  Cross-sectional  area  0.3145 
square  inch.  Outside  diameter  0.73  inch.  Weight  per  foot  1.22  pounds. 

Spacing:  7-foot  delta,  for  5oo-foot  span. 

Minimum  clearance:  30  feet  between  ground  and  lowest  conductor  at  center  of 
span. 

Temperature  range:  40°  F.  to  uo°F. 

Sleet:  0.5  inch  all  around  cables.  Diameter  of  conductor  with  sleet  1.73  inches. 
Weight  per  foot  with  sleet  1.98  pounds. 

Wind  pressure:  30  pounds  per  square  foot  normal  to  plane  surfaces. 

Test  factor  of  safety:  2. 

It  is  further  assumed  that  at  occasional  intervals  along  the  line,  the  structures 
will  be  stayed  by  guy  cables  in  the  direction  of  the  line,  and  that  the  cost  of  such 
staying  will  not  vary  with  the  length  of  span.  To  provide  in  all  structures  a  certain 
amount  of  strength  against  loads  on  the  insulators,  in  the  direction  of  the  line,  it  is 
assumed  that  in  the  tower  for  the  5oo-foot  span,  an  unbalanced  test  load  of  2000 
pounds  will  be  applied  to  the  top  of  each  insulator  pin  in  a  horizontal  direction 
parallel  to  the  line. 

In  explanation  of  the  term  "test  factor  of  safety,"  it  may  be  said  that  it  has  become 
usual  for  purchasers,  in  issuing  specifications  for  towers,  to  require  that  the  structures 
must  show,  under  actual  test,  their  ability  to  withstand  the  loads  due  to  the  assumed 
wind  pressures,  weights,  etc.,  with  a  certain  factor  of  safety.  In  calculating  the  load 
to  be  applied  to  the  top  of  an  insulator  pin,  for  instance,  to  test  it  for  strength  against 
wind  pressure  on  cables,  the  effective  area  of  the  cable  with  sleet  would  be  multiplied 
by  the  stated  wind  pressure  and  by  the  factor  2.  The  load  thus  obtained  would 
then  be  actually  applied  to  the  structure,  and  its  acceptance  would  depend  upon  its 
ability  to  withstand  such  tests.  In  order  that  the  structure  may  have  a  certain  margin 
of  strength  over  and  above  that  actually  required  to  withstand  tests  based  on  a  test 
factor  of  safety  of  2,  the  sizes  of  the  members  will  be  calculated  with  reference  to  a 
factor  of  safety  of  2.5  based  on  ultimate  strength. 

In  determining  the  sag  corresponding  to  each  length  of  span,  reference  has  been 
had  to  the  curves  given  in  Fig.  9,  calculated  by  Mr.  Ralph  D.  Mershon,  and  here 
reproduced  through  his  courtesy.  These  curves  indicate  in  each  case  the  sag  for 
maximum  temperature,  this  sag  being  so  determined  that,  when  under  minimum 
temperature  and  maximum  wind  and  sleet  loads,  the  conductor  will  not  be  stressed 
beyond  its  elastic  limit. 

With  the  foregoing  set  of  conditions  at  hand,  computations  have  been  made  of 
the  cost  of  each  of  a  series  of  structures  for  a  5oo-foot  span,  these  structures  being  of 


ELECTRICAL  TRANSMISSION. 


261 


varying  width  of  base  but  uniform  in  height.  The  purpose  of  these  computations  is 
to  show  the  relation  between  the  width  of  base  and  cost  for  such  structures,  and  to 
obtain  an  indication  as  to  what  ratio  between  height  and  width  of  base  is  most 
economical.  This  series  of  structures  is  shown  in  diagram  in  Fig.  5.  A  curve  is 
given  in  Fig.  6  showing  the  relation  between  the  width  of  base  and  the  cost  per 
structure.  The  cost  of  each  structure  has  been  figured  on  a  basis  of  $4.50  per 
100  pounds  delivered  in  the  field.  The  construction  involves  standard  angle  and 
flat  steel  sections,  standard  butt-weld  pipe,  and  some  simple  forgings.  It  has  been 


300 


4OO 


306 


tOO 


goo 


FIG.  7. 


assumed  that  all  parts  would  be  properly  galvanized,  so  no  limitation  has  been 
made  as  to  the  minimum  thickness  of  material,  it  being  simply  required  that  the 
members  be  of  sufficient  strength  to  meet  the  conditions  laid  down.  The  construc- 
tion admits  of  shipment  knocked  down  and  bundled,  and  it  is  believed  that  the 
figure  $4.50  per  100  pounds  for  structures  of  this  class  delivered  in  the  field,  is 
quite  safe. 

It  will  be  seen,  by  reference  to  the  curve  in  Fig.  6,  that  the  cost  of  the  structure 
alone  is  least  when  the  ratio  of  width  of  base  to  height  is  about  i  to  4.  This  con- 
clusion has  reference,  of  course,  only  to  the  span  of  500  feet  and  to  the  conditions  and 
type  of  construction  adopted. 


262 


HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 


The  width  of  base  of  the  structure  has  an  important  bearing  on  the  cost  of  the 
line,  aside  from  its  effect  on  the  cost  of  the  tower  structure  itself,  since  it  affects  the 
cost  of  foundations,  the  cost  of  right  of  way,  and  the  cost  of  assembling  and  raising 
the  structure  in  the  field.  Now  it  is  a  difficult  and  uncertain  matter  to  estimate  the 
variation  of  cost  of  these  items  for  a  general  case.  Hence  a  determination  of  the 
economical  width  of  base  for  certain  assumed  conditions  would  be  of  but  little  interest 
in  the  present  connection. 

Application  of  the  Formula.  The  structure  having  a  width  of  base  equal  to 
one-fourth  its  height  has  been  selected  as  a  basis  for  calculations  of  the  weights  of 
towers  for  longer  spans.  An  investigation  of  this  structure  has  been  made  to  deter- 
mine the  values  of  Ww)  WL,  Wsw,  and  WSL,  and  the  following  values  arrived  at: 


w  =  383 

.  =  813 


Wsw  -  34 
W.,   =60 


The  table  given  below  gives  the  results  obtained  by  means  of  the  formula  for  a 
series  of  towers  similar  to  No.  4  in  Fig.  5,  but  for  spans  up  to  1000  feet.  Since  all 
towers  in  the  series  are  to  be  for  the  same  wind  pressure,  p  is  equal  to  unity  in  each 
case.  Also,  r  is  proportional  to  the  length  of  span,  since  the  external  loads  are  due 
to  wind  pressure  on  the  cables  and  the  weight  of  the  cables. 

TABLE  I. 


Span. 

Sag. 

Height. 

H 

»» 

r? 

»4 

P 

r 

W3/>^W 

r.rvL 

n'pu'svt 

n*ru'sL 

w" 

200 

2.0 

32.0 

o.  780 

0.608 

Q-475 

0.370 

i 

0.4 

182 

254 

13 

15 

464 

300 

4-5 

34-5 

0.832 

0.692 

0.576 

0.479 

i 

0.6 

221 

406 

16 

25 

668 

400 

7-5 

37-5 

0.915 

0.837 

o.  766 

0.701 

i 

0.8 

294 

596 

24 

40 

954 

500 

II.  0 

41.0 

I.  00 

I.  00 

I.OO 

I.OO 

i 

I.O 

383 

813 

34 

60 

1290 

600 

15-5 

45-5 

I.  II 

1.23 

i-37 

i-5i 

i 

I.  2 

523 

1082 

52 

89 

1746 

700 

20.5 

5°-5 

1.23 

1-51 

1.86 

2.28 

i 

1.4 

7°3 

1405 

78 

128 

23M 

800 

26.0 

56.0 

1.366 

1.86    • 

2-55 

3-46 

i 

1.6 

978 

1778 

118 

179 

3053 

900 

33-o 

63.0 

1-537 

2.36 

3.62 

5-57 

i 

1.8 

I386 

2250 

190 

255 

4081 

IOOO 

40.5 

7°-5 

1.72 

2.96 

5-°9 

8.76 

i 

2.O 

195° 

2800 

298 

356 

5404 

These  results  are  shown  graphically  in  Fig.  7  by  the  curve  which  gives  the  relation 
between  the  length  of  span  and  the  cost  of  towers  per  thousand  feet  of  line.  By 
properly  representing  to  this  same  scale  the  cost  of  insulators,  foundations,  right  of 
way,  etc.,  per  thousand  feet  of  line,  corresponding  to  the  various  lengths  of  span,  and 
adding  the  corresponding  ordinates  of  all  these  curves,  a  resultant  curve  will  be 
obtained.  This  resultant  curve  will  show  the  relation  between  the  length  of  span 
and  cost  of  those  items  which  vary  with  the  length  of  span,  and  it  will  therefore  indicate 
the  economical  span  for  the  assumed  conditions. 


ELECTRICAL  TRANSMISSION. 


263 


A  curve  showing  the  cost  of  insulators  per  1000  feet  of  line  is  given  in  Fig.  7,  the 
insulators  having  been  figured  at  $5.00  each,  erected  on  the  tower  and  with  the  con- 
ductor secured  to  them. 

The  curve  in  Fig.  7,  showing  the  cost  of  foundations  per  1000  feet  of  line,  has 
reference  to  the  type  of  foundation  shown  in  Fig.  8,  and  to  the  following  method 
of  calculation. 

It  is  a  usual  assumption  that  the  strength  of  a  foundation  against  a  force  tending 
to  pull  it  out  of  the  ground  is  directly  proportional  to  the  weight  of  the  foundation 
plus  the  weight  of  earth  contained  in  the  figure  ABCD. 


If  the  foundation  in  Fig.  8  has  strength  to  resist  a  resultant  force  P,  a  second 
foundation,  exactly  similar  to  it  but  of  different  size,  would  have  strength  to  resist 
the  force  n3,  pn  being  the  ratio  between  corresponding  linear  dimensions  of  the  two 
foundations.  Now  it  seems  fair  to  assume  that  the  cost  of  such  a  foundation  would 
vary  directly  as  its  volume.  The  cost  of  the  foundation  would  therefore  vary  directly 
as  the  resultant  force  which  it  is  capable  of  resisting. 

Referring  to  some  experiments  made  at  Chicago  on  a  foundation  similar  to  that 
of  Fig.  8,  and  to  the  records  showing  the  actual  cost  of  the  foundation  in  the  field, 
ready  to  receive  the  structure,  the  following  basis  for  calculation  was  obtained: 

Resultant  force  sustained  by  foundation 24,000  Ib. 

Cost  of  foundation $15-25 

By  calculating  the  resultant  force  which  would  come  upon  the  foundation  from 
each  of  the  structures  given  in  Table  I,  and  making  the  cost  of  foundation  for  each 
structure  proportional  to  that  force,  on  the  basis  of  the  data  above  given,  the  curve 
showing  the  foundation  cost  per'  1000  feet  of  line  given  in  Fig.  7  was  obtained.  It  is 
to  be  observed  that  this  curve  is  quite  flat,  indicating  that  the  foundation  cost  does 
not  vary  to  any  great  extent  as  the  length  of  the  span  is  varied. 

The  curve  of  combined  cost  of  towers,  foundations,  and  insulators  was  obtained 
by  adding  the  respective  ordinates  of  the  curves  giving  the  separate  costs  of  these 
items.  This  curve  indicates  that,  for  the  assumed  conditions,  a  span  of  about 
425  feet  would  be  most  economical. 

It  is  to  be  observed  that  in  the  foregoing  solution  the  determining  factors  are  the 
tower  cost  and  the  insulator  cost.  As  the  price  per  insulator  is  increased,  the  econom- 


264 


HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 


ical  length  of  span  would  be  increased,  and  vice  versa;  in  other  words,  the  higher 
the  voltage  the  longer  the  span  should  be. 

For  a  low-voltage  line  the  economical  span  would  be  somewhere  between  300  and 
400  feet,  as  far  as  the  methods  of  calculation  here  employed  can  determine.  Each 
structure  in  this  case  would,  however,  be  a  very  light  affair.  It  is  probable  that  in 
the  average  case  a  somewhat  longer  span  would  be  decided  upon  in  order  to  give 
each  structure  greater  individual  strength  and  thus  make  it  safer  against  damage  due 
to  external  causes. 


too'     ,,o' 


FIG.  9. 


In  case  it  is  desirable  to  impose  limitations  of  this  sort,  the  formula  must  be  modi- 
fied accordingly,  by  subdividing  the  component  of  weight  into  parts;  as,  for  instance, 
by  letting 


_  ^  + 


+ 


+ 


where  WGl,  WG2,  WG3  and  WG4  are  components  of  weight  corresponding  to  the 
loads  Gl)  G2,  G3  and  G4  respectively. 

These  loads  may  then  be  made  to  vary  at  different  rates,  or  some  may  be  kept 
constant  and  the  others  varied  in  such  manner  as  may  be  desired.  Suppose,  for 
example,  it  is  assumed  that  each  structure  should  have  strength  to  resist  the  loads 
due  to  the  breakage  of  any  two  conductors.  These  loads  would  be  the  same  regard- 
less of  the  length  of  span,  whereas  the  loads  due  to  wind  pressure  on  the  cables 
would  vary  according  to  the  length  of  span. 

These  assumptions  will,  in  general,  tend  to  make  the  economical  span  longer. 


ELECTRICAL    TRANSMISSION. 


265 


INSULATORS. 

Pin  Insulators.  With  high-tension  transmission  systems  multi-petticoat  porce- 
lain insulators  are  extensively  used.  However,  recently  a  new  type,  known  as  the 
"  link  "  insulator,  has  been  developed.  The  petticoat  types  are  made  in  several 
sections  cemented  together,  and  with  exceptionally  large  sizes  they  are  frequently 
cemented  in  the  field.  When  this  is  done,  care  must  be  exercised  to  prevent  the 
cement  from  being  chilled  while  setting.  The  cement  mixture  must  be  a  fine  rich 
mortar  free  from  impurities. 

Porcelain  for  electrical  purposes 1  is  a  mixture  of  ground  flint  or  silicon  dioxide 
and  feldspar  (KjO.A^Og.SiO^,  potassium  aluminum  silicate,  raised  to  the  vitrifying 
temperature,  that  is,  to  a  temperature  sufficiently  high  to  melt  the  feldspar  and  per- 
mit it  to  unite  the  particles  of  flint  into  a  perfectly  homogeneous  body  of  uniform 
electrical  and  mechanical  strength. 


FIG.   i. — Insulator  for  6o,ooo-volt  used  on 
the  Kern  River  Transmission  System. 


FIG.  2. — 5o,ooo-volt   Insulator  used  on  the 
Taylor's  Falls  Transmission  System. 


Besides  the  electrical  stresses,  the  insulators  must  be  made  strong  enough  to  with- 
stand mechanical  stresses  imposed  on  them  by  the  span.  Mechanically,  insulators 
can  be  designed  for  any  load  by  the  proper  disposition  of  material.  Good  electrical 
porcelain  has  a  crushing  strength  in  excess  of  15,000  pounds,  and  tensile  strength 
ranging  between  1500  and  2000  pounds  per  square  inch.  Fig.  i  shows  an  insulator 
as  installed  at  the  Kern  River  Plant.2  The  specification  called  for  a  guarantee  of  a 
ioo,ooo-volt  test  from  the  groove  to  the  pin  for  half  an  hour,  under  a  precipitation  of 
i  inch  in  5  minutes,  at  an  angle  of  30  degrees  from  the  vertical.  The  assembled 
insulator  was  required  to  withstand  under  a  wet  test  a  potential  of  150,000  volts 
for  30  seconds,  and  the  separate  parts  are  guaranteed  to  withstand  a  voltage  of  25  per 

1  "High   Voltage    Insulator    Manufacture,"   by   Walter   T.    Goddard.      Canadian  Society   of   Civil 
Engineers,  Dec.  19,  1907. 

2  Kern  River  Plant  No.  i.     Electrical  World,  Aug.  31,  1907. 


266  HYDROELECTRIC    DEVELOPMENTS   AND   ENGINEERING. 

cent  in  excess  of  the  normal  proportion  of  over-voltage  test.  The  insulators  are 
guaranteed  to  withstand  a  side  strain  of  4000  pounds,  and  actually  fail  at  approxi- 
mately 9000  pounds. 

A  cross  section  of  the  insulator  used  on  the  Taylor's  Falls  5o,ooo-volt  transmission 
system1  is  seen  in  Fig.  2.  It  is  known  as  the  S.W.  No.  i,  made  by  the  Locke 
Insulator  Manufacturing  Company.  It  consists  of  four  parts  held  together  with 
neat  cement.  These  insulators  are  shipped  in  crates  assembled,  but  without  pins. 
The  crates  were  provided  with  holes  just  the  size  to  take  the  pin.  The  cement- 
ing in  of  pins  was  done  before  the  insulators  were  uncrated,  the  crate  thus  serving 
the  purpose  of  a  template  to  hold  the  pins  in  position  while  the  cement  dried.  The 
insulator,  as  seen  by  the  drawing,  is  12^  inches  high  by  14  inches  in  diameter  over  all. 
The  four  parts  were  tested  before  assembling  with  a  6o-cycle,  2oo-kilovolt-ampere 
testing  set.  The  top  piece  withstood  a  test  pressure  of  60,000  volts;  the  second  shell 
40,000  volts;  the  third  shell,  50,000  volts;  and  the  fourth  inner  shell  or  center,  50,000 
volts.  The  assembled  insulator  without  cement  was  tested  at  120,000  volts. 

The  experience  of  noted  Swiss  and  Italian  engineers  in  the  development  of  high- 
tension  insulators  is  summed  up  in  an  article  entitled,  "Present  Status  of  European 
Practice  in  Transmission  Line  Work,"2  of  which  the  following  is  an  extract: 

"  The  experiences  of  Mr.  Charles  Brown,  one  of  the  earliest  workers  in  this  field, 
and  a  pioneer  of  many  of  the  more  recent  developments,  gives  a  word  of  warning  to 
those  engaged  in  insulator  testing,  claiming  that  most  insulators  have  a  very  pro- 
nounced fatigue  effect.  Though  an  insulator  may  stand  a  given  tension  for  15  min- 
utes, it  may  possibly  break  down  at  this  tension  if  it  is  maintained  for  two  hours. 
He  recalls  the  great  difficulty  always  experienced  in  attempts  to  deduce  reliable 
results  from  any  testing,  except  actual  use  on  the  transmission  line.  He  further  states 
that  very  little  trouble  is  experienced  from  heavy  rainstorms  or  climatic  conditions 
causing  insulator  breakdowns,  the  trouble  being  almost  entirely  mechanical  and  due 
to  lightning.  Such  mechanical  defects  as  have  been  experienced  are  thought  to  be 
due  largely  to  the  use  of  cement  for  connecting  the  petticoats  of  the  insulators  together, 
since  great  difficulty  is  experienced  in  obtaining  a  cement  which  does  not  swell  with 
increase  of  temperature  and  thus  fracture  the  insulator.  In  Switzerland,  use  is  made 
of  sulphur  cement  (when  sulphur  is  used,  the  pins  must  be  galvanized)  and  plaster 
of  Paris,  both  of  which  have  given  satisfaction.  The  latter,  however,  being  some- 
what porous,  must  be  varnished  with  shellac  wherever  it  is  exposed  to  the  air  at  the 
outside  of  joints,  etc. 

"  For  fixing  the  pins  of  the  insulators,  tow  or  hemp  is  used,  which  is  twisted  around 
the  end  of  the  pin,  the  whole  being  then  dipped  in  asphalt  or  shellac  and  screwed  into 
the  insulator.  Mr.  Brown  states  that  no  splitting  or  fracturing  of  insulators  occurs 
with  this  method  of  fixing  the  pins. 

"  It  is  further  stated  that  no  good  results  have  been  obtained  with  the  Fox  cement, 
which  is  thought  to  have  too  high  a  coefficient  of  expansion,  producing  splitting 

1  The  50,000- Volt  Line  of  the  Taylor's  Falls,  Minneapolis,  Power  Transmission.       Electrical  World, 
Sept.  7,  1907. 

2  Electrical  World,  Dec.  22,  1906. 


.itu    uiimiui  f\  A 

I INIY    OF  C»A 

ter  country 


ELECTRICAL    TRANSMISSION. 

troubles.     In  this  connection,  however,  it  should  be  noted  that  somewhat  thinner 

'  *  m    m   M.  •   f  *  *" 

insulators  are  used  in  Switzerland  than  in  Italy,  and  the  engineers  of  the  li 
have  found  very  little  trouble  due  to  this  cause. 

"  Other  Swiss  experts  have  referred  to  the  difficulty  in  the  manufacture  of  perfect 
insulators,  pointing  out  that  minute  holes  in  the  enamel  in  the  surface  which  cannot 
be  seen  by  the  eye,  may  pass  test,  and  then  cause  breakdown  after  some  months' 
installation. 

"  Some  again  claim  to  have  overcome  the  difficulty  due  to  insulator  splitting,  by 
using  no  cement  at  all,  the  insulator  being  made  in  two  or  more  pieces  which  are 
tested  independently  and  then  screwed  together  and  the  whole  rebaked. 

"  They  have  also  paid  considerable  attention  to  the  exact  shaping  of  the  edges  of 
the  insulator  petticoats,  a  rounded  edge  being  considered  very  bad,  since  in  a  heavy 
rainstorm  it  will  cause  the  water  to  run  under  and  drop  on  the  surface  of  the  lower 
petticoats.  They  at  present  very  much  favor  a  petticoat  slightly  turned  up  near  the 
edge  to  check  the  velocity  of  the  running  water  and  then  dropping  to  a  sharp  point 
on  the  extreme  edge,  which  seems  to  prevent  this  running  under.  By  this  means  it  is 
considered  that  the  effect  of  rainstorms  may  be  considerably  reduced.  For  all 
transmission  lines  for  electromotive  forces  of  40,000  volts  and  above,  iron  poles  are 
preferred,  and  if  the  insulators  have  not  more  than  two  petticoats,  wooden  cross-beams 
are  used;  if  three  or  more,  then  they  are  placed  directly  on  the  iron  poles. 

"  In  Italy,  Mr.  Guido  Semenza,  whose  name  is  associated  with  the  well-known 
Paderno  transmission  and  numerous  others  throughout  the  country,  referring  to  his 
early  experiences,  stated  that  on  the  Paderno  line,  after  some  experiment,  his  conical 
type  of  insulator  was  chosen  and  a  triple  petticoat  was  used;  the  line  being,  however, 
finally  completed  with  two  of  these  cemented  together  as  one  six-petticoat  insulator, 
The  dimensions  of  this  were,  height  over  all,  7  inches;  diameter  of  petticoat,  6f  inches. 
In  other  plants  the  Paderno  type  has  been  superseded  by  a  much  lighter  insulator, 
but  it  has  lately  returned  to  favor  and  is  in  general  use.  The  original  Paderno 
insulator  is  shown  in  Fig.  3." 

This  type  of  insulator  has  also  been  installed  on  the  5o,ooo-volt  system  of  the 
Brusio  plant.  It  is  fastened  to  the  pins  by  hemp  and  shellac  as  above  described. 
The  pins  are  mounted  on  wooden  blocks,  secured  to  the  steel  cross-arm. 

On  many  European  high-tension  tranmissions  systems,  the  insulators  are  made 
in  one  piece  to  eliminate  cementing.  Such  insulators  are  employed  on  the  35,000- 
volt  transmission  system  of  the  Urfttalsperre  plant,  Germany. 

Suspension  Insulators.  A  new  type  of  insulator  successfully  used  in  recent  practice 
is  the  suspension  type.  The  advantages  of  this  type  over  the  pin  insulator  are  given 
by  Mr.  Goddard  as  follows:1 

"The  reason  for  using  suspended  insulators  is  largely  a  matter  of  cost,  since  it  is 
entirely  possible  to  build  porcelain  insulators  of  the  conventional  type  of  sufficient 
size  to  successfully  operate  at  any  voltage,  but  the  extreme  height  and  diameter  of 

1  High  Voltage  Insulator  Manufacture,  by  Walter  T.  Goddard.  Canadian  Society  oj  Civil  Engineers, 
Dec.  19,  1907. 


268  HYDROELECTRIC  DEVELOPMENTS  AND  ENGINEERING. 

a  pin-type  insulator  for  100,000  or  150,000  volts  makes  the  cost  prohibitive.  A  sus- 
pended type  of  insulator  has  several  advantages  which  it  is  well  to  understand  before 
going  into  details  of  design.  Of  paramount  importance  is  the  unit  formation  making 
it  possible  to  increase  the  effective  insulation  whenever  it  is  desired  to  raise  the  line 
voltage  or  wherever  it  seems  desirable  to  present  extra  leakage  surface  because  of 


FIG.  3. — Paderno  Type  Insulator 
for  40,000  to  50,000  Volts. 


FIG.  4. — Suspended  Insulator,  showing 
the  Progressive  Breaking  Down  be- 
tween the  Beginning  of  Actual  Leak- 
age and  the  Maximum  Arc. 


salt  fogs  or  smoke  from  railways  and  factories.  Many  lines  start  operation  at  much 
lower  potential  than  designed  for,  because  the  initial  load  is  light,  and  the  potential 
need  be  increased  only  when  regulation  demands  it.  With  the  pin  type  of  insulator 
there  is  no  alternative  but  to  invest  at  the  start  in  the  largest  insulators  which  the 
line  will  ever  need,  whereas  in  the  suspended  form,  additional  units  may  be  intro- 
duced whenever  the  growth  of  power  business  warrants  an  increase  in  potential. 
In  the  pin  type  of  insulator  the  nearness  of  line  wire  and  pin  must  always  prove  a 
weak  point  for  lightning  assault  as  well  as  an  aggravator  of  line-charging  current 
difficulties.  The  suspended  type  gets  away  from  both  difficulties  by  a  wide  separa- 
tion of  line  conductor  and  supporting  structure.  Incidentally  the  position  of  the 


ELECTRICAL    TRANSMISSION. 


269 


conductor  below  the  cross-arm  permits  the  supporting  structure  to  act  as  a  lightning 
rod  and  so  to  relieve  the  line  of  much  lightning  stress. 

"  Mechanically,  provision  must  be  made  to  prevent  the  swinging  conductor  from 
coming  too  near  the  tower  structure,  but  the  extra  length  of  cross-arm  necessitated 
by  this  feature  is  more  than  compensated  for  in  cost  by  the  fact  that  there  are  no 
twisting  strains  upon  the  arm.  Insulator  unit  formation  presents  another  very  posi- 
tive advantage  in  the  matter  of  breakage.  When  a  shell  of  a  pin-type  insulator 


FIG.  5. — Method  of  Suspending  Insulators.          FIG.  6. — Detail  of  a  Dead  Ending. 


becomes  cracked  or  broken  the  whole  device  is  rendered  worthless,  as  it  is  utterly 
impossible  to  break  the  cement  joint  forming  the  bond  between  shells.  Further, 
the  cracking  of  a  shell,  especially  an  inner  shell,  may  cause  immediate  shut-down, 
or  at  least  shut-down  during  the  first  severe  rainstorm.  On  the  contrary,  the  break- 
ing or  cracking  of  one  of  the  shells  of  a  suspended-unit  type  insulator  takes  away 
but  that  one  unit  from  the  series;  thus,  in  the  case  of  a  five-unit,  100,000- volt  insulator, 
a  broken  unit  reduces  the  total  strength  but  twenty  per  cent. 


270 


HYDROELECTRIC    DEVELOPMENTS    AND    ENGINEERING. 


"  The  underhung  system  of  insulation  works  out  with  pleasing  directness  and 
simplicity,  and  its  comparative  cheapness  argues  for  its  wide  adoption  for  the  higher 

voltages.  The  cost  of  such  insulators,  as  at 
present  manufactured,  ranges  from  $1.60  to 
$2.00  per  unit,  depending  on  the  nature  of  the 
fittings. 

"At  least  two  14-inch  units  would  be  required 
for  60,000  volts,  and  as  good  6o,ooo-volt  insula- 
tors can  be  secured  for  prices  ranging  from  $1.70 
to  $2.30  each,  the  question  of  the  use  of  sus- 
pended units  for  voltages  below  75,000  to 
80,000  is  largely  one  of  safety  factor  and 
investment. 

"  The  foregoing  has  given  little  which  could 
be  used    in    the   determination    of    the    proper 
insulator  to  use  for  any  particular  voltage,  and  it 
is  quite  in  point  to  add  here,  that  every  case  is 
special.     Insulators   well  suited  to  one  locality 
are  out  of  reason  for  use  elsewhere.     A  single 
transmission    line    of   less   than    100    miles    in 
FIG.  7.— Suspended  Insulators  as  used  length     may     easily     pass     from     high,     clear 
in  the    no.ooo-volt  System  of  the  ,    •         .  r  ,. 

Grand  Rapids  Muskegon  Power  Co.,    mountam    air    to    f°ggy>    sm°ky    surroundings 
General  Electric  Co.  which    are    a  constant  menace  to  continuity  of 

service. 

Again,   the  cost  of  complete  immunity  may   well  be  balanced  against  cost  of 
possible  shut-downs." 


FIG.  8. — Dead-End  Insulator  of  the  Suspended  Type. 
General  Electric  Co. 


FIG.  9. — Single  Desk 
of  Suspended  In- 
sulator. 


A  detail  of  the  Locke  Suspended  Insulator  is  given  in  Fig.  4,  while  two  other 
illustrations  give  the  method  of  application  of  same.  The  dead-ending  scheme  as 
proposed  for  all  towers  has  the  advantage  that  in  case  of  a  breakdown  of  a  conductor 


ELECTRICAL    TRANSMISSION. 


271 


FIGS.  10  and  n.—  Application  of  Cooke  Strain  Insulators. 


FIG.  12. — Diagram  of  Anchor  Insulators. 


FIG.  13. — Insulating  and  Rolling   Support  for  Long   Spans,  Tofwehult-Westerwik  Trans- 
mission System,  Sweden. 


2/2 


HYDROELECTRIC    DEVELOPMENTS    AND    ENGINEERING. 


adjacent  sections  do  not  have  to  be  slacked  down  in  order  to  repair  the  break.  The 
disadvantage  is  that  the  line  conductor  has  to  be  cut  up  into  sections,  the  current 
being  by-passed  by  a  loop  or  "  jumper  "  as  seen  in  the  illustration. 

A  suspended  type  of  insulator  is  used  on  the  1 10,000- volt  transmission  system  of 
the  Muskegon  Grand  Rapids  Power  Company.  They  are  of  the  type  described  by 
Mr.  Hewlett  in  his  paper  presented  at  the  last  convention  of  the  American  Institute 
of  Electrical  Engineers,  at  Niagara  Falls,  June  26,  1907.  Figs.  7  and  8  show  the 
construction  of  the  members  of  this  insulator.  Five  of  these  insulators  are  suspended 
in  series  to  insulate  the  line.  The  diameter  of  each  porcelain  link  is  10  inches,  and 
the  rated  voltage  that  each  link  will  withstand  is  25,000,  although  the  links  arc  over 
where  wet  at  approximately  60,000  volts  each.  Fig.  9,  while  showing  the  interior 


FIG.  14. — Porcelain  Base  Insulator  Pins. 


FIG.  15. — All  Steel  Insulator  Pins. 


construction,  also  shows  the  form  of  petticoat  on  the  insulator  used  in  a  horizontal 
position  as  a  strain  insulator  at  curves  and  at  intervals  to  anchor  the  line.  The  spans 
of  this  line  are  on  the  average  about  150  feet.  The  conductors  consist  of  stranded 
copper  cables  with  hemp  centers,  having  a  conductivity  equal  to  No.  2  solid  wire. 
This  line  was  designed  for  100,000  volts,  but  recently  the  voltage  has  been  raised 
to  1 10,000.' 

Strain  Insulators.  Strain  insulators  must  be  placed  at  the  beginning  and  end  of 
lines,  and  at  all  sharp  turns  to  take  up  the  pull  of  the  spans  which  ordinary  insulators 
cannot  stand.  Such  insulators  as  seen  in  Figs.  10  and  n  are  usually  held  at  top  and 
bottom. 

Two  or  more  ordinary  insulators,  when  used  in  connection  with  an  anchoring 

1  Editorial,  Engineering  Record,  Aug.  15,  1908. 


ELECTRICAL    TRANSMISSION. 


273 


FIG.  17. —  Insulator  with  Single  Tie. 
6o,ooo-volt  Insulator  of  the  Ontario 
Power  Co. 


FIG.  16. — Detail  of    Iron  Insulator  Pin,  used 
for  Insulators  seen  in  Figs.  17  and  18. 


FIG.  18.  —  Insulator  with  Clamp. 
6o,ooo-volt  Insulators  of  the  Ontario 
Power  Co.  Upper  and  Lower  Insu- 
lators are  of  Uniform  Size. 


274  HYDROELECTRIC    DEVELOPMENTS    AND   ENGINEERING. 

device,  may  take  the  place  of  a  regular  strain  insulator.  An  arrangement  of  such 
insulators  has  been  installed  in  the  transmission  system  of  the  Pennsylvania  Rail- 
road Company.1  The  insulators  are  placed  one  behind  the  other,  each  couple 
forming  an  anchor  insulator  and  practically  eliminating  all  danger  of  wires  breaking 
at  the  insulators,  as  shown  in  Fig.  12.  The  two  cross-arms  provide  accommodation  for 
1 8  wires,  but  at  the  present  time  only  10  are  in  use.  The  height  of  the  first  row  of 
insulators  from  the  floor  of  the  platform  is  7  feet  6  inches,  and  of  the  top  row,  10  feet 
6  inches.  This  gives  an  abundance  of  room  for  linemen  to  work  with  safety. 

The  insulators  are  placed  longitudinally  3  feet  between  centers,  with  the  exception 
of  the  third  insulator  from  each  end,  which  is  placed  3  feet  6  inches  from  the  second. 
This  variation  permits  of  symmetrical  spacing  with  reference  to  the  upright  supports 
of  the  cross-arms.  They  measure  6|  inches  across  the  umbrella  and  are  6  inches  high, 
each  insulator  having  two  petticoats.  They  were  designed  for  a  voltage  of  25,000, 
but  the  present  service  pressure  is  only  13,000  volts. 

Insulator  Pins.  Wooden  pins  have  been  extensively  used  on  transmission  systems 
up  to  30,000  volts.  However,  in  localities  subject  to  salt  storms,  heavy  sea  fogs  and 
near  chemical  manufactories,  there  has  been  more  or  less  pin  burning  without  regard 
to  the  type  of  insulator  used,  or  the  voltage  of  the  system.  It  has  been  reported2  that 
certain  plants  using  only  440  volts,  have  at  times  great  trouble  from  the  burning  of 
pins,  although  io,ooo-volt  insulators  are  used.  To  overcome  such  difficulties,  pins 
are  provided  with  porcelain  bases.  Nearly  all  wooden  pins  are  made  of  locust,  oak 
or  eucalyptus,  and  are  chemically  treated  for  preservation.  All  standard  wooden  pins 
are  i  inch  in  diameter  and  have  4  threads  per  inch.  A  modification  of  the  wooden  pin 
to-day  more  commonly  used,  is  an  iron  bolt  with  a  wooden  top  which  screws  into  the 
insulator,  and  is  provided  with  a  porcelain  base.  Such  a  pin  is  illustrated  in  Fig.  14. 
A  still  more  satisfactory  type  for  high-tension  transmission  is  an  all-steel  pin  as  seen 
in  Fig.  15.  It  is  made  in  various  modifications  and  used  on  wooden  cross-arms  as 
well  as  steel.  Sometimes  the  steel  pin  is  made  in  a  single  piece,  either  forged  or  cast, 
a  type  of  which  is  illustrated  in  connection  with  the  insulators  of  the  Ontario  Power 
Company  (see  Fig.  16). 

Method  of  Tying  Conductors.  The  tying  of  the  line  conductor  to  the  insulator 
is  done  in  different  ways;  such  as  the  patent  Clark  system  or  as  illustrated  in 
the  accompanying  illustrations.  Figs.  17  and  18  show  the  methods  adopted  by  the 
Ontario  Power  Company.  One  shows  aluminum  tie  wires;  and  in  the  other,  the 
conductor  is  held  in  place  by  a  clamp  on  a  cast  iron  cap  cemented  to  the  insulator. 
These  insulators  are  14  inches  in  diameter  and  are  designed  for  the  6o,ooo-volt  trans- 
mission system.  They  are  about  27  inches  high  including  the  steel  cast  pin,  and 
weigh  about  80  pounds. 

Section  Switches.  Section  switches  are  located  where  duplicate  lines  run  parallel 
and  near  each  other,  so  that,  in  emergency  cases,  defective  sections  may  be  easily 
cut  out  and  by-passed.  They  are  also  located  at  places  where,  in  the  near  future, 

1  Steel  Transmission  Towers  on  the  Jersey  Meadows.     Electrical  World,  Dec.  14,  1907. 

2  Burning  of  Wooden  Pins  on  High  Tension  Transmission  Lines,  by  C.  C.  Chesney.    Am.  Inst.  E.  E., 
March,  1903. 


ELECTRICAL    TRANSMISSION. 


275 


TV     7ZX 


r  

FIG.  19. — Line  Disconnecting  Switch. 


Attach  Grounding 
Cabll  of  (Jpermtlng 
Poll. 


FIG.  20. — Open  Air  Section  Switch. 


I     fel 


FIG.  21. — Outdoor  Two  Break  Section  Switch  used  on  the  Pacific  Coast. 


*NL«s 

Standard^ 

Cpnorclion 


Bolt 
»"*  4*H*rd  Wood 


276 


FIGS.  22  and  23. — Typical  Wall  Outlets. 


ELECTRICAL    TRANSMISSION. 


277 


taps  will  have  to  be  made.  The  common  section  switch  is  nothing  more  than  a 
disconnecting  switch  such  as  used  in  the  generating  station,  but  usually  larger  and 
heavier,  and  mounted  on  line  insulators.  They  are  usually  placed  directly  in  the 
line,  similar  to  that  shown  in  Fig.  20,  which  has  been  installed  in  a  transmission  system 


FIGS.  24  and  25. — Typical  Wall  Outlets.     Locke  Insulator  Company. 


FIG.  26.— Provo,  Permanent  Wall  Outlet.     Three  Concentric  Tubes  of  Fibre  Conduit. 

in  Auburn,  N.Y.     Where  section  houses  are  located  in  long  transmission  lines,  the 
section  switches  are  preferably  placed  in  the  houses. 

Another  type  of  section  switch  as  used  on  the  Pacific  coast,  is  seen  in  Fig.  21. 
It  will  be  noticed  that  the  blades  of  the  switch  revolve  and  can  be  operated  from  the 
ground. 


278  HYDROELECTRIC    DEVELOPMENTS    AND   ENGINEERING. 

Wall  Outlets.  Where  high-tension  wires  leave  or  enter  a  building,  the  outlet 
must  be  protected  against  the  weather.  This  is  accomplished  in  American  practice, 
by  building  hoods  over  the  wall  opening  as  seen  in  some  of  the  accompanying  illus- 
trations. Other  methods  are,  by  inserting  insulating  bushings  in  the  wall.  Common 
Continental  practice  is  to  lead  the  conductor  through  a  hole  of  a  glass  panel;  the  hole 
is  from  one-fourth  to  three-eighths  of  an  inch  larger  than  the  line  conductor. 
Insulators  are  placed  on  both  sides  of  the  panel  so  that  the  section  of  the  conductor 
going  through  the  wall  is  always  straight.  There  are  no  hoods  or  other  protection 
provided,  and  it  is  a  simple  and  inexpensive  yet  efficient  arrangement. 

Many  Western  plants  and  those  on  the  Pacific  coast  have,  for  a  wall  outlet, 
a  tile  pipe,  18  to  24  inches,  provided  with  a  plate  glass  cover.  Tile  pipes  and  bushings 
used  for  wall  outlets  must  be  set  on  the  slant,  so  that  collected  moisture  can  drain 
off  outdoors. 

BIBLIOGRAPHY. 

HIGH  TENSION  POWER  TRANSMISSION.     1906.     A  Series  of  Papers  and  Discussions  at  the  Meetings  of 

the  A.  I.  E.  E.  under  the  Auspices  of  Committee  on  High  Tension  Power  Transmission.  Vol.  I, 

1906. 

THE  ELECTRICAL  TRANSMISSION  OF  ENERGY.    A.  V.  Abbott.     1907. 
LINE  CONSTANTS  AND  ABNORMAL  VOLTAGES  AND  CURRENTS  IN  HIGH-POTENTIAL  TRANSMISSIONS. 

E.  J.  Berg.     Proc.  Am.  Inst.  E.  E.,  September,  1907. 
THE  GROUNDED  NEUTRAL,  WITH  AND  WITHOUT  SERIES  RESISTANCE  IN  HIGH  -TENSION  SYSTEMS. 

P.  M.  Lincoln.     Proc.  Am.  Inst.  E.  E.,  September,  1907. 
LINE  CONSTRUCTION  FOR  OVERHEAD  LIGHT  AND  POWER  SERVICE.     Paul  Spencer.    Canadian  Elec- 

trical News,  September,  1906. 
A  NEW  TYPE  OF  INSULATOR  FOR  HIGH  TENSION  TRANSMISSION  LINES.    E.  M.  Hewlett,    Proc.  Am. 

Inst.  E.  E.,  June,  1907. 
SQME  NEW  METHODS  IN  HIGH-TENSION  LINE  CONSTRUCTION.     H.  W.  Buck.    Proc.  Am.  Inst.  E.  E., 

June,  1907. 
HIGH-TENSION  INSULATORS,  FROM  AN  ENGINEERING  AND  COMMERCIAL  STANDPOINT.     C.  E.  Delafield. 

Electrical  Review,  N.Y.,  Sept.  28,  1907. 
THE  CORONA  EFFECT  AND  ITS  INFLUENCE  ON  THE  DESIGN  OF  HIGH  TENSION  TRANSMISSION  LINES. 

Lamar  Lyndon.     Am.  Inst.  E.  E.,  Philadelphia  Section,  Nov.  9,  1909. 
TRANSMISSION  LINE  CROSSINGS  OVER  RAILROADS.    Ralph  D.  Mershon.    Railroad  Gazette,  Feb.  7, 

1908. 

THE  CENTRAL  STATION  DISTRIBUTING  SYSTEM.    H.  B.  Gear.    Electrical  Age,  January,  1908. 
AMPERES  IN  ALTERNATING-CURRENT  CIRCUITS.    A.  D.  Williams,  Jr.    Electrical  World,  Aug.  8,  1908. 
GROUND  DETECTORS  AND  THEIR  CONNECTIONS.     James  T.  Coe.     American  Electrician,  December, 


THE  DISTRIBUTION  OF  PRESSURE  AND  CURRENT  OVER  ALTERNATING-CURRENT  CIRCUITS.    A.  E. 

Kennely.     Harvard  Engineering  Journal,  November,  1905. 

SIMPLE  DIAGRAMS  FOR  THREE-PHASE  POWER  CALCULATIONS.    Alfred  Still.    Power,  March,  1906. 
PRESENT  STATUS  OF  EUROPEAN  PRACTICE  IN  TRANSMISSION  LINE  WORK.    Electrical  World,  Dec.  22, 

1906. 

SOME  POWER  TRANSMISSION  ECONOMICS.    Frank  G.  Baum.    Proc.  Am.  Inst.  E.  E.,  May,  1907. 
HIGH-PRESSURE  DIRECT  CURRENT  TRANSMISSION.    Electrical  Review,  London,  June  7,  1907. 
THE  TRANSMISSION  OF  ELECTRICAL  ENERGY  BY  DIRECT  CURRENT.      J.  S.  Highfield.     Inst.  E.  E. 

March  7,   1907. 


ELECTRICAL  TRANSMISSION.  279 

POTENTIAL  STRESSES  AS  AFFECTED  BY  OVERHEAD  GROUNDED  CONDUCTORS.    R.  P.  Jackson.    Proc. 

Am.  Inst.  E.  E.,  April,  1907. 
EARTHING  THE  NEUTRAL,  WITH  AND  WITHOUT  SERIES  RESISTANCE  IN  HIGH  TENSION  SYSTEMS.    Paul 

M.  Lincoln.     Proc.  Am.  Inst.  E.  E.,  September,  1907. 

THE  GROUNDED  NEUTRAL.     F.  G.  Clark.     Proc.  Am.  I.  E.  E.,  September,  1907. 
RECENT  PRACTICE  IN  ELECTRICAL  TRANSMISSION  OF  POWER.     W.  B.  Esson.    Engineer,  London, 

Dec.  14,  1906. 
PRESSURE  RISE  ON  HIGH  TENSION  TRANSMISSION  LINES.     E.  Hudson.    Electrical  Engineer,  London, 

April  26,  1907. 

EXPERIMENTS  WITH  HIGH  POTENTIALS.     Electrical  World,  Jan.  26,  1907. 
LINE  CONSTANTS  AND  ABNORMAL  VOLTAGES  AND  CURRENTS  IN  HIGH-POTENTIAL  TRANSMISSIONS. 

Ernst  J.  Berg.     Proc.  Am.  Inst.  E.  E.,  September,  1907. 
THE  LOCALIZATION  OF  EARTH  LEAKAGES  ON  A  THREE-WIRE  NETWORK.    Electrical  Engineer,  London, 

April  12,  1907. 
PROTECTIVE  DEVICES  FOR  HIGH  TENSION  TRANSMISSION  CIRCUITS.     J.  S.  Peck.    Institute  of  Electrical 

Engineers,  March,  1908. 

DETERMINING  THE  SIZES  OF  ALTERNATING  CURRENT  LINE  WIRES.    N.  T.  Carl.    Power,  July  28,  1908. 
LONG  DISTANCE  ELECTRIC  TRANSMISSION  OF  POWER.    L.  S.  Bruner.    Proc.  Engr's  Club  of  Phila., 

April,  1908. 
A  TRANSMISSION  LINE  CONSIDERED  AS  A  MECHANICAL  STRUCTURE.    W.  T.  Ryan.    Electrical  World, 

Feb.  29,  1908. 
COMPENSATION  OF  PRESSURE  VARIATIONS  ON  ALTERNATING  CURRENT  NETWORK  SUPPLYING  MOTORS. 

A.  Heyland.     Electrician,  London,  April  24,  1908. 
THE  TANGENTIAL  SYSTEM  OF  SUSPENDING  OVERHEAD  TROLLEY  AND  TRANSMISSION  WIRES.    Robert 

N.  Tweedy.     Electrician,  London,  May  15,  1908. 
SOME  FEATURES  OF  EUROPEAN  HIGH  TENSION  PRACTICE.     Frank  Koester.     Electrical  Age,  December, 

1908. 

SOME  POWER  TRANSMISSION  ECONOMICS.    F.  G.  Baum.    Proc.  Am.  Inst.  E.  E.,  May,  1907. 
ONE-PHASE  HIGH -TENSION  POWER  TRANSMISSION.     E.  J.  Young.   Proc.  Am.  Inst.  E.  E.,  May,  1907. 
INDUCTIVE  DISTURBANCE  IN  TELEPHONE  LINES.    Louis  Cohen.    Proc.  Am.  Inst.  E.  E.,  May,  1907. 
TRANSMISSION-LINE  TOWERS  AND  ECONOMICAL  SPANS.    D.  R.  Scholes.    Proc.  Am.  Inst.  E.  E.,  May, 

1907. 
POTENTIAL  STRESSES  AS  AFFECTED  BY  OVERHEAD  GROUNDED  CONDUCTORS.    R.  P.  Jackson.    Proc. 

Am.  Inst.  E.  E.,  April,  1907. 

HlGH-VOLTAGE  DIRECT-CURRENT  AND  ALTERNATING-CURRENT  SYSTEMS  FOR  INTERURBAN  RAILWAYS. 

W.  J.  Davis,  Jr.     Proc.  Am.  Inst.  E.  E.,  August,  1907. 


CHAPTER   IX. 
SUBSTATIONS. 

GENERAL    ARRANGEMENT. 

Location  of  Substations.  Substations  or  receiving  stations  are  designed  to  act  as 
distributing  centers  for  light  and  power.  Where  a  source  of  direct  current  is  desired, 
the  substation  houses,  rotary  converters,  or  motor  generators  set. 

The  substations  as  a  rule  are  located  as  near  as  possible  to  the  center  of  gravity 
of  their  systems  of  distribution.  This  cannot  always  be  done,  as  the  demands  on 
the  station  vary  in  certain  sections  during  the  different  seasons,  particularly  in  street 
railroad  work.  In  many  cases,  to  help  out  in  the  latter  instance,  portable  sub- 
stations are  run  to  the  centers  of  increased  demand,  and  remain  until  the  load  on  the 
line  can  be  taken  care  of  by  the  substation  proper. 

Size  of  Units.  The  size  of  units,  may  they  be  generators,  transformers,  converters 
or  motor  generator  sets,  depends  upon  the  capacity  of  the  plant  and  upon  the  load 
factor.  Care  must  be  taken  to  have  one  or  two  units  in  reserve,  depending  upon  the 
size  of  the  plants.  American  practice  is  to  overload  the  units  50  per  cent,  while 
European,  only  20  to  30  per  cent. 

Fixed  rules  as  regards  the  size  of  the  individual  capacities  cannot  be  laid  down, 
as  they  all  depend  on  the  nature  of  loads  at  various  times.  Each  case  has  to  be 
individually  treated,  which  is  best  done  by  plotting  load  curves  for  the  day,  week, 
and  possibly  for  the  month;  in  many  instances  it  is  necessary  to  plot  curves  for  the 
whole  year,  particularly  for  suburban  railways,  and  heavy  lighting  loads,  where 
great  fluctuations  occur  during  certain  seasons  of  the  year. 

Arrangement  of  Substation.  In  transformer  substations,  transformers  are  usually 
located  in  fireproof  compartments,  provided  with  iron  rolling  shutters.  To  facili- 
tate inspection  and  repairs,  a  track  is  run  in  front  of  the  compartments,  so  that  the 
transformers  may  be  readily  removed  on  a  small  truck  and  then  shifted  to  the  repair 
room.  Such  transformers  are  provided  with  wheels  and  ratchet,  resting  on  a  rack. 
The  truck  is  also  provided  with  a  rack  so  that  the  transformers  are  easily  shifted  to 
the  truck  without  the  aid  of  an  overhead  crane.  Where  converters  are  used,  the 
transformers  are  not  housed  in  compartments,  but  are  set  opposite  the  converter  on 
the  main  floor,  where  they  are  handled  by  an  overhead  crane. 

Figs,  i  and  2  show  typical  arrangements  of  transformers,  switchboards,  con- 
verters, etc.  It  will  be  observed  that  the  substation  of  the  Connecticut  Railway  and 
Lighting  Company  is  provided  with  a  large  storage  battery;  for  such  auxiliaries 
separate  apartments  are  required. 

280 


SUBSTATIONS. 


281 


282 


HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 


A  very  novel  arrangement  of  a  substation  is  that  at  Piattamala,  Italy.  The 
transformers  are  arranged  in  two  banks  each,  to  accommodate  twelve  I250-K.W. 
7ooo/5o,ooo-volt  single-phase,  oil-cooled  transformers.  The  current  is  received 
at  one  end  of  the  building;  the  two  sets  of  low-voltage  busses  are  located  on  a 


FIG.  2. — Cross  Section  of  Waterbury  Substation. 

mezzanine  floor  above  the  passage  between  the  banks  of  transformers.     The  current 
leaves  at  the  other  end  of  the  building. 

Ventilation.  In  laying  out  a  substation,  it  must  be  borne  in  mind  that  even  the 
normal  operation  of  the  transformers  and  converters  will  considerably  increase  the 
temperature,  therefore  provision  must  be  made  for  good  ventilation.  This  is  par- 
ticularly important  where  oil-cooled  transformers  are  used.  It  is  unnecessary  to 
provide  any  auxiliary  means  for  heating  in  compact  substations  which  carry  a  station 
load  factor  equal  to  average  practice,  and  run  24  hours  per  day. 

Drainage.  Where  air-blast  transformers  are  used,  the  air  chambers  must  be 
waterproofed  and  the  ducts  located  at  such  an  elevation  that  water  will  not  stand  in  the 
bottom.  If  this  is  not  done,  the  transformer  may  be  damaged  by  the  warm  air  from 
the  blowers  picking  up  moisture  and  depositing  it  in  the  transformers  not  in  service. 
Where  any  cable  comes  into  the  station,  underground,  the  entering  conduit  must  be 
sealed,  and  suitable  drainage  provided,  so  that  water  cannot  leak  through  these  open- 
ings. Where  oil-cooled  transformers  are  installed,  it  is  good  practice  to  provide  a 
pit  of  sufficient  capacity  to  hold  the  oil  from  several  transformers,  and  also  drainage- 
piping  from  the  oil  drain  cocks  on  the  transformers  to  the  pit.  These  pipes  must  be 
of  ample  size,  so  that  the  oil  can  be  drained  off  very  quickly  in  case  of  emergency. 

Air  Compressor.  An  air  compressor  is  an  item  which  must  never  be  overlooked 
in  a  substation  as  well  as  in  a  power  house  of  any  considerable  size,  as  the  life  of 
all  electrical  apparatus  depends  to  a  very  great  extent  upon  cleanliness. 


SUBSTATIONS. 


^ 


m^^s^^^^^ 


284 


HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 


FIG.  4.  —  Plan  and  Sectional  Elevation  of  Small  Substation  with  Single-phase  Oil-insulated 
Self-cooling  Transformers  and  Hand-operated  Oil  Switches,  11,000  or  i3,2Oo-volt, 
Overhead  High  Tension  Lines. 


SUBSTATIONS. 


285 


£ 

*      •§ 

H 


O 
bO 
CO 

.o 
"S 

•4-» 

cfl 

J2 

CO 


I 

i 


o 


286 


HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 


Frequently,  a  portable  motor-compressor  with  a  small  storage  tank  is  used. 
Where  stationary  compressors  are  used,  the  air  must  be  piped  from  the  tank  to  various 
points  in  the  station,  where  cocks  must  be  provided  for  the  attachment  of  a  rubber 
hose.  An  air-pump  governor  is  a  convenient  means  for  keeping  the  air  in  the  storage 
tank  at  a  constant  pressure. 

TRANSFORMERS. 

Types  of  Transformers.  Transformers  are  made  either  single  phase  or  three 
phase,  and  in  shell  or  core  type.  The  core  type  is  more  extensively  used  abroad  and 
made  three  phase.  In  America,  besides  the  core  type,  the  shell  type  is  widely  used, 
but  chiefly  in  single-phase  design. 

The  advantage  of  a  three-phase  transformer  is  its  greater  compactness  and 
lighter  weight,  resulting  in  a  considerable  saving  in  first  cost  of  transformer  itself,  and 
a  saving  in  floor  space  of  about  30  per  cent.  The  connections  of  the  transformers 
are  simpler  and  fewer  than  in  three  single-phase  units.  The  method  of  winding  and 
insulating  is  practically  the  same  as  in  single-phase  transformers. 


FIG.  i . — Shell  Type  Transformer  in  Process 
of  Construction,  General  Electric  Co. 


FIG.  2. — Core  Type  Transformer  in  Pro- 
cess of  Construction. 


The  difference  between  a  shell  and  core-type  transformer  is  best  illustrated  in 
Fig.  i.  In  the  shell  type,  it  will  be  noticed  that  the  coils  are  almost  entirely  sur- 
rounded by  the  sheet  steel  laminations,  and  are  known  as  "  pancake  "  coils.  To 
secure  mechanical  strength,  the  conductors  must  be  rectangular  in  cross  section 


SUBSTATIONS. 


287 


and  of  sufficient  width.  As  the  "  pancake  "  coil  is  difficult  to  wind  for  a  small 
transformer,  the  core  type  is  preferable  for  small  sizes. 

In  the  core  type,  the  core  is  made  of  sheet  steel  laminations  and  almost  entirely 
surrounded  by  the  winding,  giving  it  great  stability  and  mechanical  strength,  for 
which  reason  it  is  used  for  small  as  well  as  large  size  transformers.  The  coils  are 
made  of  flat  copper  strips  wound  on  edge.  The  secondary  or  low  potential  wind- 
ings of  these  transformers  are  usually  divided  into  two  or  more  coils  connected  in 
series,  on  each  of  the  vertical  legs  of  the  core. 

The  coils  in  the  secondary  windings  of  pole  transformers  have  their  leads  run  to  a 
common  terminal  block.  By  interconnecting  the  terminals  with  jumpers,  a  limited 


FIG.  3. — 2000-K.W.,  4ooo/6o,ooo-volt  Gen- 
eral Electric  Co.'s  Shell  Type  Trans- 
former. 


FIG.  4. — i6oo-K.V.A.,  4o,ooo/5oo-volt  3- 
phase  Water  Cooled  Oil  Transformer, 
Ocrlikon  Co. 


range  of  voltages  may  be  impressed  on  the  service  mains.     The  high  tension  wind- 
ings are  arranged  for  series  or  multiple  connection  with  other  transformers. 

Characteristics  of  Transformers.  Aside  from  the  reliability  and  safety  of  operation 
of  a  transformer,  the  most  important  electrical  features  are  the  efficiency  and  the 
regulation.  Although  good  regulation  and  good  efficiency  are  always  to  be  desired, 
the  relative  importance  of  the  two  is  determined  by  the  local  conditions  under  which 
the  transformer  is  to  operate. 


288 


HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 


Where  power  is  expensive  or  is  used  at  only  short  intervals,  the  efficiency  of  the 
transformer,  especially  at  light  loads,  is  of  great  importance,  but  where  the  power  is 
cheap,  the  efficiency  as  a  rule  is  not  so  important  a  feature. 

On  account  of  the  low  cost  of  the  power  and  the  double  transformation  of  the 
potential  necessary,  the  important  feature  of  transformers  designed  for  use  on  high 
voltage  circuits,  is  the  regulation  and  not  the  efficiency,  especially  not  the  efficiency  at 
light  loads. 

Regulation  of  Transformers.  In  large  transformers  for  long-distance  transmission, 
close  regulation  is  of  even  greater  importance  than  in  the  ordinary  small  transformer 
for  lighting  circuits,  as  the  drop  in  the  line  is  often  of  considerable  magnitude;  and 


WESTINGHOUSE  AIR  BLAST  TRANSFORMER. 
550  K.W.  10500  VOLTS.  3000  ALTERNATIONS. 


50  75  JOO 

PEK  CENT  LOAD 

CHART  I. 


125 


150 


with  raising  and  lowering  transformers,  the  transformer  drop  occurs  twice  between 
the  generator  and  the  load.  This  drop  is  generally  increased  when  the  power  factor 
of  the  load  falls  below  unity,  as  is  usual  in  power  work.  It  is  therefore  particularly 
necessary  that  close  regulation  be  obtained  in  the  transformers  designed  for  trans- 
mission work,  especially  if  they  are  to  be  used  for  supplying  inductive  loads. 

Transformers  for  such  service  are  usually  designed  to  have  good  regulation  for 
loads  of  any  power  factor.  The  second  set  of  curves,  Chart  I,  illustrates  the  operating 
characteristics  of  a  transformer  designed  for  transmission  work  where  the  power 
factor  of  the  circuit  is  low. 


SUBSTATIONS. 


289 


The  regulation  of  a  transformer  depends  largely  upon  the  resistance  drop,  and 
the  inductive  drop  within  it.  The  former  is  fixed  by  the  amount  of  copper  loss  at 
full  load,  the  latter  by  the  number  of  turns  in  the  winding  and  the  relative  position 
of  the  coils  and  the  space  between  them. 

In  a  transformer  designed  for  good  regulation,  it  is  therefore  essential  to  have 
the  two  windings  as  close  together  as  possible,  a  result  obtainable  only  by  using  the 
best  insulating  materials  to  separate  them,  and  to  have  low  copper  loss  at  full  load. 

Some  stations  supply  a  service  where  the  transformers  are  connected  to  the  supply 
mains  continuously,  and  current  is  taken  from  the  secondary  for  only  a  few  hours 
during  the  day.  In  such  a  case,  the  iron  losses  are  incessant  and  the  copper  losses 
intermittent.  The  transformer  must  be  of  such  a  design  that  the  iron  losses  are 
the  lowest  possible,  otherwise  the  total  work  received  during  the  day  will  greatly 
exceed  the  work  given  out.  The  ratio  of  the  work  given  out  to  the  work  received 
during  the  day  is  called  the  all-day  efficiency. 


o 

3 

D 
0 

u 

OC 

•*. 

1.8 

1.- 
1.4 

1.2 
1.0 
.8 
.6 
.4 
.2 
0 

0 

z 
ui 

u 
u. 
u. 
u 
•w. 
100 

90 
80 
TO 
60 
50 
40 
30 
20 
10 
0 

WESTINGHOUSE  AIR  BLAST  TRANSFORMER. 
100  K.W.  12000  VOLTS.  3000  ALTERNATIONS. 

x 

L  — 

EFF 

ICIEtv 

CY 

/ 

7 

,^- 



—               '• 

—  £§ 

ouu 

HON_ 

^£ 

*T-FO 

/ 

X 

Ji^4 

«. 

*--^ 

1 

^^ 

^ 

<n-T^ 

^j 

T^^* 

.  — 

—  ^= 

_  — 

— 

-— 

' 

IRON 

LOSS 

^^ 

^ 

0SSu. 

^-^* 

^ 

^-" 

~ 

—  — 

K) 

.   — 

,  

co£S&2^ 

s 

0 

8 

} 

70 

i.  PbWER 

60 
FACTOR 

,1 

I, 

S 

0 

&                 SO                 75                100               125               150 
_£LOAD 

CHART  II. 

Efficiency  of  Transformers.  The  efficiency  of  transformers  depends  on  the  losses, 
which  are  of  two  kinds,  viz.,  iron  and  copper.  The  former  is  due  to  magnetic  rever- 
sals in  the  iron  and  practically  constant  for  all  loads.  To  obtain  a  high  efficiency 
at  small  loads  the  iron  losses  must  be  extremely  low,  as  will  be  seen  in  Chart  II. 
The  copper  losses  result  from  the  passage  of  current  through  the  conductor,  and  are 
very  low  for  high  efficiency  at  full  load.  In  general,  it  may  be  stated  that  the  efficiency 
of  transformers  is  from  97  to  98.5  per  cent. 


290  HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 

Connections.  Transformers  are  connected  in  a  variety  of  ways  for  transmission 
work:  single  phase,  2-phase,  3-phase-delta,  3-phase-star,  3-phase-T,  3-phase- V, 
2-phase-3-phase,  3-phase-star  and  delta.  These  connections  give  equal  voltages 
across  any  leg. 

For  3-phase-star  or  delta  connections,  three  single-phase  transformers  are 
necessary.  In  the  star  or  Y-connection,  three  corresponding  terminals  are  joined 
in  a  common  point.  In  the  delta  connection,  the  terminals  must  be  so  connected 
that  the  windings  form  a  continuous  or  closed  circuit;  like  terminals  must  not  be 
connected;  this  causes  bucking. 

The  Scott  method  of  connecting  two  transformers  of  equal  capacity  affords  a 
very  convenient  means  for  obtaining  a  2-phase-3-phase  transformation,  or  vice  versa. 
It  is  seldom  used  for  long-distance  transmission  work. 

The  high  and  low  tension  windings  of  both  transformers  have  taps  brought  out 
from  the  middle  and  86  per  cent  points.  By  connecting  the  86  per  cent  point  of  one 
to  the  mid  point  of  the  corresponding  winding  of  the  other,  the  transformers  will  give 
a  2  or  3-phase  conversion  with  voltage  transformation,  according  to  the  phase  of  the 
supply  mains. 

On  low  tension,  supply  and  service  2-phase  lines,  where  two  transformers  are 
used,  the  system  can  be  reduced  from  a  four  to  a  three-wire  by  connecting  the  two 
transformers  in  series;  one  line  to  each  of  the  free  terminals,  and  the  third  to  the 
junction  of  the  two. 

The  choice  of  connections  affects  the  design  of  the  transformers  to  be  employed. 
With  Y-connections,  each  transformer  is  wound  for  only  58  per  cent  of  the  line  poten- 
tial, and  for  full  line  current.  On  the  other  hand,  A-connections  require  windings 
for  full  line  potential,  and  only  58  per  cent  of  the  line  current.  From  this,  the 
Y-connection  requires  only  58  per  cent  of  the  windings  needed  in  a  delta  connection, 
with  the  conductor  cross  section  correspondingly  greater. 

It  is  readily  seen  that  more  windings  with  their  insulation  necessitates  larger  and 
more  expensive  coils;  this,  in  turn,  calls  for  a  longer  magnetic  circuit,  consequently 
a  large  and  heavy  transformer. 

Where  the  transformer  current  is  heavy,  a  conductor  of  large  cross  section  is 
necessary.  To  accomplish  the  same  end,  the  windings  are  split  into  multiple  circuits 
of  small  cross  section,  and  can  be  easily  handled. 

Trouble  with  one  transformer  in  a  Y-connection  renders  the  bank  inoperative. 
Any  one  of  the  transformers  in  a  delta  group  may  be  cut  out,  and  the  remainder  will 
still  deliver  3-phase  power  up  to  two-thirds  capacity  of  the  entire  bank. 

As  a  rule,  most  Y-connected  systems  have  the  common  or  neutral  point  grounded. 
Occasionally,  the  neutral  point,  instead  of  being  grounded,  is  connected  to  a  main, 
thus  making  a  4-wire  3-phase  system  possible.  The  voltage  between  this  and  any  of 
the  mains  is  58  per  cent  of  that  between  any  of  the  phases.  This  practice  is  con- 
fined to  low-tension  service  distribution. 

Delta  vs.  Y-Connections.  Delta-connected  transformer  primaries  have  been 
customarily  used,  to  permit  operation  with  two  transformers  in  case  of  trouble  with 
the  third.  It  has  not  been  usually  appreciated,  that  with  the  primary  windings 


SUBSTATIONS. 


291 


vwwwwwv    vwwwvww 
/WW\A 


Two-Phase 


yvwwvvvvv\www~vwwvwwvwvy 


Three  -Phase  T 
Wft/wwwvwwww    vwvwvwwww 


/WWtvAAAA    K/V 

!'«4- 


KAAAAAAA 


Six-Phase  T 


vwwwww  wwvwwvv  vwwwwvv 


iwwy 

AAAAA  AAAAA  AAAAA 


VWWVWAA/    VWWWWW    VWWWWW 


Three  -Phase  A 


VwwwwJ  Uvwwww1  wwwwwv 


tww\  kww. 

2 


Three -Phase  Y 

VwwwwvW   vwvvwwvw   vwvwwww 
AA/VNAA3 


Six -Phase  Diametrical 


Wvwww  vwwwww  vwvwwwv 

Ij 


2't 


v  AAAAA 


Six-Phase  Y  Six-Phase  A 

FIG.  5. — Method  of  connecting  Transformers  to  Rotary  Converters. 


HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 


Y-connected  with  the  neutral  solidly  grounded,  and  with  the  high-tension  neutral  of 
the  generating  system  also  grounded,  three-phase  or  six-phase  converters  may  be 
started  and  successfully  operated  with  two  transformers  per  converter,  in  case  of 
trouble  with  the  third.1 

The  output  in  either  of  the  above  emergency  cases  is,  of  course,  limited  to  that  of 
the  transformers  in  use.  With  the  grounded  Y-connections,  the  service  may  be  main- 
tained in  case  of  trouble  on  one  phase  of  the  transmission  line,  the  other  two  wires 
and  ground  serving  as  the  circuit. 

Should  three-phase  shell-type  transformers  be  installed  with  high-tension  delta 
or  grounded  Y-connections,  two  phases  may  be  likewise  operated,  provided  both 
windings  of  the  third  phase  are  disconnected  and  short-circuited.  The  output  of  the 
unit  is  limited  in  this  case,  to  the  capacity  of  the  two  transformers  or  phases,  instead 
of  the  three. 

Transformers  for  higher  pressures  than  20,000  volts  must  be  used  Y-connected 
with  primary  neutral  grounded,  but  may  be  operated  delta  at  0.57  times  their  rated 
Y- voltage,  if  initially  lower  voltages  are  wanted  than  those  for  which  they  are  designed. 

Oil-Cooled  Transformers.  The  oil-cooled  transformer  is  the  most  extensively 
used,  for  the  reason  that  oil  is  a  better  heat-conducting  medium  than  air;  besides,  oil 
preserves  the  insulation,  keeping  it  soft  and  pliable,  and  prevents  oxidization  by  air; 


FOR  DMUGE:>  at 

FIG.  6. — Forced  Oil  Circulation  for  cooling  Oil-Insulated  Transformers. 

consequently  the  use  of  oil  maintains  a  uniform  core  loss  and  a  superior  insulation. 
The  oil  in  the  transformer  is  cooled,  either  by  its  natural  gravity  circulation  or  by 
means  of  submerged  coils  through  which  water  is  circulated. 

The  amount  of  water  necessary  for  cooling  the  oil  depends  on  the  temperature  of 
the  incoming  and  outgoing  water.  Theoretically,  each  kilowatt  loss  will  give  up 
57  B.t.u.  per  minute,  or,  in  other  words,  57  pounds  of  water  are  raised  i°  F.  In 
practice,  however,  the  amount  of  water  required  varies  with  the  design,  and  the 
amount  of  water  necessary  can  be  obtained  from  the  manufacturer. 

1  See  paper,  Y  or  A  Connections  of  Transformers,  by  F.  O.  Blackwell,  presented  at  aoth  Annual  Con- 
vention Am.  Inst.  E.  E.,  Niagara  Falls,  N.Y.,  July  i,  1903. 


SUBSTATIONS. 


293 


Another  design  of  transformer,  instead  of  using  water  coils,  the  upper  part  of  the 
transformer  is  provided  with  submerged  radiating  ribs  cooled  by  circulating  water. 
Transformers  of  this  design,  having  a  capacity  of  1250  K.V.A.,  7700/50,000  volts, 
have  been  installed  at  the  Italian  substation  at  Piattamala. 


FIG.  7. — Method  of  Cooling  Circulating  Water  for  6750-K.V.A.  6600/66, ooo-volt  3-Phase 
Siemens-Schuckert  Transformer,  Molinar  Plant,  Spain. 

In  order  to  keep  the  temperature  rise  of  this  transformer  below  45°  C.,  5  gallons 
of  water  per  minute  at  a  temperature  of  15°  C.  are  required.  For  a  25  per  cent  over- 
load for  6  hours,  10  gallons  are  required;  for  2  hours  at  same 
overload  and  using  5  gallons,  the  permissible  temperature  rise 
is  60°  C. 

Forced  Oil-Cooled  Transformer.  Another  method  of  cool- 
ing the  transformer  oil,  is  by  forced  circulation,  and  has  the 
advantage  of  doing  away  with  the  cooling  coils.  Instead  of 
the  oil  being  cooled  in  the  transformer,  it  is  cooled  outside  in 
a  cooling  device  which  works  on  the  same  principle  as  a  cooling 
pond  or  a  surface  condenser. 

A  very  elaborate  system  of  this  kind  is  given  in  Fig.  6.1 
It  will  be  observed  that  besides  water  pumps,  a  set  of  oil 
pumps  is  necessary,  while  with  the  water-cooled  system,  only 
water  pumps  were  required.  Where  sufficient  head  is  obtain- 
able, the  water-pumps  may,  of  course,  be  eliminated. 

With  a  forced-oil  circulation,  the  transformers  are  small 
and  less  expensive,  due  to  the  elimination  of  cooling  coils; 
however,  an  extra  cooling  system  is  necessary,  the  cost  of 
which  in  small  plants  will  outstrip  the  reduced  cost  in  trans- 
transformer  plants  over  4000  K.W.,  the  forced-oil  system  seems 


FIG.  8.— Air-Cooled 
Transformer 


formers.      In 
preferable. 

Air-Cooled  Transformers.    In  the  early  type  of  transformers,  the  cooling  was  done 
by  natural  air-draft,  or  forced  draft.     The  latter  is  still  very  much  in  use.     The  cores 

1  Forced-Oil  and  Forced- Water  Circulation  for  Cooling  Oil  Insulated  Transformers,  by  C.  C.  Chesney. 
Am.  Inst.  E.  E.,  April,  1907. 


294 


HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 


of  the  transformer  are  incased,  through  which  air  is  forced  by  means  of  a  blower. 
Where  there  are  a  number  of  transformers,  they  are  preferably  set  over  a  common 
duct  and  supplied  with  air  from  a  blower  at  either  end,  one  being  kept  in  reserve. 
They  are  most  conveniently  operated  by  motors.  The  volume  of  air  required  for  air- 
blast  transformers  depends  on  the  outside  temperature,  as  well  as  the  entering  and 


1 

1 

1 

V 


I 

"    PPiTg 

1  /  L  j  L  /  x  /  z    ~J 

'$ 

/ 
/ 

2 

>7//?  CHAM&ER 

/ 

FIG.  9. — Arrangement  of  Air  Blast  Transformers. 

discharge  temperature,  and  to  great  extent  on  the  design.  Under  normal  load  and 
continuous  operation,  the  temperature  rise  must  not  exceed  35  to  40°  C;  at  25  per 
cent  overload,  50°  C. ;  at  50  per  cent  overload,  60°  C.  The  temperature  rise  is 
taken  by  thermometers  or  calculated  from  the  increase  in  resistance.  The  pressure 
furnished  by  the  blowers  depends  on  their  size  and  the  length  of  the  ducts.  High- 
voltage  transformers  usually  require  higher  air  pressure.  Fig.  10  gives  approximately 
the  air  pressure  required  for  different  capacity  transformers.  A  more  complete  table 
on  this  subject  is  found  in  Table  I. 

TABLE    I. —  AIR    REQUIRED    FOR    TRANSFORMERS. 


Horse 

Total 
kilowatt 
trans. 

Size  of 
units 
kilowatt. 

Cubic  feet 
air  required 
per  transformer 
per  minute. 

Cubic  feet 
air  required 
for  all 
transformers 

Cubic  feet 
air  furnished 
by  standard 
blower  set. 

Oz. 

Press. 

Freq. 
Mot'r  . 

Size 
blower, 
inches  . 

Speed 
blower. 

power  to 
drive 
blower  full 
vol.  and 

per  min. 

pressure. 

900 

IOO 

45° 

4,050 

6,OOO 

} 

25 

5° 

75° 

2-5 

40 

5° 

800 

^ 

60 

40 

900 

1800 

200 

90x5 

8,100 

8,000 

1 

25 

55 

75o 

4 

40 

55 

800 

60 

5° 

900 

2700 

300 

1125 

10,125 

10,000 

1 

25 

55 

75o 

5 

40 

55 

800 

60 

55 

720 

4500 

500 

1625 

14,625 

14,000 

'     1 

25 

75 

500 

5-5 

40 

70 

600 

60 

70 

720 

6750 

75° 

1875 

16,875 

2O,OOO 

\ 

25 

90 

500 

12 

40 

80 

600 

60 

80 

600 

7500 

1250 

2800 

16,800 

20,OOO 

I 

25 

90 

500 

12 

40 

80 

600 

60 

80 

600 

SUBSTATIONS. 
60  CYCLES. 


295 


Volls. 

2200 

66OO 

1  1  000 

16500 

22OOO 

33000 

K\v. 

100 

2OO 
250 
300 

375 

500 

1000 

1500 

2OOO 
2500 
3000 

* 

Oz.  Pres 

sure 

sure 

a 

Oz.  Pres 

Oz.  Pres 

sure 

i 

25  CYCLE  TABLE 


Volts. 

22OO 

6600 

IIOOO 

16500 

22000 

33000 

Kw. 

IOO 

125 

\ 

Oz.  Pres 

sure 

15° 

2OO 

1 

250 

1 

300 

1 

375 

500 

3 
4 

Oz.  Pres 

sure 

75° 

1 

JOOO 

1 

1500 

2OOO 

I 

Oz.  Pres 

sure 

2500 

3000 

FIG.  10. — Air  Required  for  Transformers. 


296  HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 

With  air-cooled  transformers,  more  or  less  dirt  is  carried  along  with  the  air,  and 
deposited  along  the  various  air  passages.  Much  of  the  dirt  may  be  obviated  by 
keeping  the  air  passages  to  and  from,  the  transformer  closed  when  not  in  use.  A 
frequent  cleaning  of  the  transformer  windings  with  a  blast  of  compressed  air  will 
improve  conditions,  and  at  the  same  time  remove  a  possible  fire  risk. 

Oil-insulated  transformers  should  have  the  oil  drained  off  once  in  a  while,  and 
all  evidences  of  sediment  removed.  The  emergency  drains  must  be  cleaned  out  at 
the  same  time. 

In  a  recent  Italian  plant  at  Lomazzo,  I25O-K.V.A.,  4 2, 000/11,000- volt  trans- 
formers without  casing,  are  placed  in  masonry  compartments,  through  which  the  air 
is  forced  from  ducts  beneath.  Each  compartment,  reaching  to  the  ceiling,  is  provided 
with  a  ventilator.  The  reason  given,  is,  that  ready  inspection  can  be  made  without 
removing  the  core,  although  provision  is  made  for  doing  so  in  case  of  extensive 
repairs. 

The  guaranteed  and  test  efficiencies  of  these  transformers  is  as  follows: 

Regulation  at  cos<£  =  i.oo  full  load i  per  cent 

Regulation  at  cos</>  =  0.80  full  load 3  per  cent 

Regulation  at  short  circuit 3  per  cent 

Efficiency  full  load .97  per  cent 

Efficiency  half  load 9.65  per  cent 

The  operation  of  the  blowers  is  included  in  the  above-named  efficiencies. 

CONVERTERS. 

Rotary  converters  are  installed  for  transforming  alternating  current  into  direct 
current;  however,  they  may  be  otherwise  used.  They  may  be  supplied  with  direct 
current  and  deliver  alternating.  They  may  be  connected  to  alternating  mains  and 
operate  as  simple  synchronous  motors,  or  connected  to  direct  current  mains  and 
operated  as  simple  direct  current  motors.  There  are  a  number  of  other  electrical 
and  mechanical  connections  which  can  be  applied,  but  the  main  purpose  is  to  serve 
as  a  means  of  conversion  from  alternating  to  direct  current. 

In  general  appearance  and  construction,  the  rotary  converter  resembles  a  direct 
current  generator  to  which  a  set  of  collecting  rings  has  been  added.  The  field  is 
composed  of  a  cast  iron  yoke  with  inwardly  projecting  poles  of  laminated  steel.  It 
may  be  either  shunt  or  compound  wound.  The  armature  consists  of  a  slotted, 
laminated  core  with  embedded  coils,  with  the  addition  of  taps  or  leads  to  the  collector 
rings. 

The  method  of  cross-connecting  the  armature  windings,  which  has  been  a  means 
of  securing  superior  performance  in  direct  current  generators,  is  applied  to  rotary 
converters  with  equal  success.  This  is  an  effective  way  of  preventing  sparking  at 
the  commutator,  as  it  insures  uniform  field  strength  under  all  the  poles. 

Voltage  and  Frequency.  The  ratio  between  the  voltages  at  the  alternating  and 
direct  current  ends  of  a  given  rotary  converter,  is  approximately  constant,  and  cannot 


SUBSTATIONS. 


297 


be  changed  by  altering  the  speed  or  by  using  a  rheostat.  Therefore,  any  alteration 
in  one  voltage  will  proportionately  alter  the  other,  and  vice  versa.  In  most  rotary 
converters,  the  voltage  on  the  collector  rings  of  a  two-phase  machine  is  about  seven- 
tenths  of  that  at  the  commutator,  and  the  voltage  on  the  collector  rings  of  a  three- 
phase  rotary  converter  is  about  six-tenths  of  that  on  the  commutator. 


FIG.  i. — Rotary  Converters  in  Sub-Station  "  d,"  Albina,  Portland  Railway  Light  and  Power 

Company. 

Thus,  a  two-phase  converter  receiving  alternating  current  at  approximately 
385  volts  will  deliver  direct  current  at  550  volts,  and  a  three-phase  converter  receiving 
alternating  current  at  approximately  330  volts  alternating  current  will  deliver  at 
550  volts  direct  current. 

In  installations  supplying  three-wire  lighting  systems,  or  where  it  is  necessary  to 
obtain  two  voltages,  for  the  operation  of  variable  speed,  direct  current  motors,  a 
special  neutral-wire  connection  is  required  for  use  in  conjunction  with  the  positive 
and  negative  leads  on  the  direct  current  side  of  the  rotary.  If  a  conductor  be  con- 
nected to  the  middle  points  of  the  secondary  windings  of  the  transformers,  which 
supply  the  alternating  current  for  a  two-phase  rotary,  it  will  be  found  that  the  E.M.F. 
between  this  conductor  and  either  of  the  direct  current  terminals  is  equal  to  one-half 
of  the  E.M.F.  between  those  terminals.  In  this  way  no  volts  can  be  secured  from 
a  22o-volt  machine.  A  similar  arrangement  for  three-phase  rotaries  is  secured  by 
employing  the  interconnected  star  system  of  connections  for  the  secondary  winding 
of  the  transformers,  the  neutral  lead  being  connected  at  the  common  junction  point 
of  the  secondary  windings. 

The  same  relation  exists  between  speed,  number  of  poles  and  frequency  that  is 


298  HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 

found  in  alternating  current  generators.     The  product  of  the  number  of  poles  by  the 
speed,  in  revolutions  per  minute,  is  equal  to  the  number  of  alternations  per  minute. 

Rotary  converters  can  be  had  for  any  frequency  up  to  60  cycles  per  second.  The 
standard  frequencies  are  25  and  60  cycles,  the  former  being  generally  used  for  rail- 
way service,  and  the  latter  when  a  combined  railway  and  lighting  service  is  operated, 
or  where  power  is  obtained  from  existing  6o-cycle  transmission  plants. 

Phases.  The  alternating  current  may  be  applied  to  the  collector  rings  of  the 
rotary  converter  in  the  form  of  either  single,  two,  three  or  six  phase  currents.  How- 
ever, single-phase  currents  are  seldom  used,  and  the  majority  of  machines  are  wound 
for  either  three  or  six  phases.  It  is  now  general  practice  to  wind  25  cycle  units  for 
railway  work  for  three  phases  when  under  500  K.W.  capacity,  and  for  six  phases  when 
of  500  K.W.  or  above.  In  6o-cycle  machines,  those  under  300  K.W.  are  wound 
three-phase,  and  300  K.W.  and  above,  six-phase.  Six-phase  winding  in  the  larger 
machines  is  highly  desirable,  because  it  reduces  the  heating,  and  increases  the  effi- 
ciency and  stability  of  operation. 

Field  Connections.  For  highly  fluctuating  loads,  such  as  those  on  interurban  or 
small  city  railway  systems,  rotary  converters  with  compound-wound  fields  are  prefer- 
able. The  compounding  of  such  machines  differs  from  that  of  direct  current  gen- 
erators; the  direct  current  voltage  is  dependent  upon  the  alternating  current  voltage, 
and  is  therefore  affected  by  the  line  drop,  generator  voltage,  etc.  The  standard  com- 
pound winding  is  designed  to  give  600  volts  at  both  no  load  and  full  load,  that  is,  a 
flat  compounding,  with  5  per  cent  drop  between  the  generating  station  and  the 
rotary  converter  substation.  This  flat  compounding  is  obtained  with  the  assistance 
of  reactive  coils  connected  between  the  stepdown  transformers  and  the  rotary  con- 
verter. The  compound-wound  field  coils  are  of  the  ventilated  type,  that  is,  the 
winding  is  in  two  layers  separated  by  a  space  through  which  air  is  blown  by  the 
centrifugal  action  of  the  armature,  thus  greatly  increasing  the  radiating  surface  of 
the  field  spools  and  reducing  the  temperature  rise. 

The  utility  of  reactance  will  readily  be  understood  when  it  is  borne  in  mind  that 
a  rotary  converter  is  simply  a  transforming  device,  and  the  ratio  of  the  alternating 
voltage  impressed  to  the  direct  voltage  delivered,  is  approximately  a  fixed  quantity 
and  independent  of  the  field  strength.  Therefore,  any  increase  in  the  direct  current 
voltage,  or  overcompounding,  must  be  secured  by  a  proportional  increase  of  pressure 
at  the  collector  rings,  and  it  is  the  presence  of  a  reactance  in  circuit  which  brings 
about  this  desired  result.  Or,  in  other  words,  by  inserting  this  reactance,  the  line 
itself  has  been  compounded,  and  thus  made  self-regulating. 

In  order  to  make  use  of  single-pole  switchboards  and  to  do  away  with  pedestals, 
each  compound-wound  rotary  converter  is  fitted  with  a  panel  mounted  on  the  machine 
frame,  and  carries  the  equalizer  switch,  as  well  as  a  switch  used  in  connection  with 
the  shunt  provided  for  the  adjustment  of  the  series  winding. 

In  order  to  make  the  rotary  converter  panels  of  the  switchboard  of  the  same 
polarity  as  the  direct  current  feeder  panels  (positive  or  trolley  polarity),  the  series 
fields  are  connected  on  the  negative  or  ground  side  of  the  circuit  between  the  armature 
and  the  rail  returns;  this  makes  all  switches  on  the  machine  frame  panel  of  the  negative 


SUBSTATIONS.  299 

or  ground  potential.  A  double-throw  field  break-up  switch  is  also  included  in  the 
machine  equipment,  by  means  of  which  the  polarity  of  the  machine  may  be  reversed 
if  necessary,  in  starting. 

Where  the  load  is  practically  constant,  such  as  in  heavy  services,  shunt-wound 
rotary  converters  are  more  generally  used.  In  such  cases,  the  fluctuations  of  the  load 
are  so  low  that  they  can  be  followed  by  hand  control  of  the  field  rheostats. 

Starting  of  Converters.  There  are  different  ways  to  throw  converters  on  the  line 
starting  from  rest.  One  way  is  to  supply  the  converter  with  a  separate  starting 
motor  or  one  mounted  on  the  shaft,  which  brings  the  machine  up  to  the  desired 
speed,  and  with  the  application  of  an  automatic  synchronizer,  the  converter  is  thrown 
on  the  line  at  the  first  instant  of  synchronism,  and  the  starting  motor  cut  off. 
Another  method  is  by  supplying  alternating  current  directly  to  the  slip  rings,  and  is 
impressed  upon  the  windings  at  a  lower  voltage  than  is  used  after  the  machine  is 
run  up  to  speed,  and  is  in  synchronism  with  the  source  of  supply.  This  low-voltage 
alternating  current  is  obtained  from  the  stepdown  transformer  by  means  of  switches, 
which  connect  the  armature  to  low-voltage  taps  on  the  transformers  at  starting,  and 
establish  the  connections  to  the  full-voltage  taps  when  the  machine  has  reached 
synchronous  speed. 

The  most  common  method  used  in  street  railroad  work,  is  to  start  the  converter 
as  a  direct  current  motor,  supplied  with  current  from  the  trolley  mains.  By  adjust- 
ing the  strength  of  the  field  windings,  synchronous  speed  is  reached  and  the  machine 
thrown  on  the  line.  This  method  does  not  require  any  special  starting  apparatus, 
such  as  starting  motors,  or  transformers  with  special  taps.  Its  disadvantage  lies  in 
the  fact  that  it  is  dependent  on  the  direct  current  supply  of  the  system. 

Hunting.  Rotary  converters,  to  give  the  best  service,  must  run  in  exact  synchro- 
nism with  the  supply  current,  but  it  frequently  occurs  that  the  speed  of  the  generator 
is  not  exactly  uniform;  and  in  such  cases,  the  rotary  will  tend  to  follow  the  fluctua- 
tions of  the  generator  speed,  resulting  in  a  surging  action  of  the  rotary  armature, 
alternately  above  and  below  synchronism.  This  is  commonly  known  as  "hunting," 
and  often  assumes  disastrous  proportions  where  no  provisions  are  made  for  counter- 
acting this  effect.  Since  hunting  is  an  oscillation  in  the  relative  positions  of  the 
converter  —  ajiead  of  the  generator  at  one  instant  and  behind  the  next  —  the  correc- 
tive currents  in  the  circuit  due  to  the  oscillations  are  first  in  one  direction  and  then  in 
the  opposite.  The  effect  of  this  varying  current  is  to  strengthen  the  leading  pole 
tip  when  flowing  in  one  direction  and  to  strengthen  the  lagging  pole  tip  when  flowing 
in  the  other  direction,  thus  constantly  changing  the  distribution  of  magnetism  over 
the  pole  face,  and,  in  effect,  causing  the  magnetic  flux  to  continually  shift  back  and 
forth  across  the  pole  face.  . 

The  fact  that  hunting  is  always  accompanied  by  a  shifting  field  makes  possiLI,- 
an  effective  method  of  reducing  it.  Most  rotaries  are  provided  with  heavy  copper 
grids,  that  surround  each  pole  face  and  extend  across  it,  embedded  in  one  or  more 
slots.  The  function  of  the  copper  grids  is  to  act  as  dampers,  preventing  the  relative 
position  of  the  converter  armature  being  changed,  by  the  corrective  currents,  more 
than  the  initial  change  in  the  generator.  The  action  is  essentially  a  damping  one, 


300 


HYDROELECTRIC    DEVELOPMENTS   AND  ENGINEERING. 


and  is  the  same  as  that  of  the  copper  magnet  damper  used  in  galvanometers,  and  is 
analogous  to  the  action  of  a  dashpot  on  an  engine  governor. 

To  consider  the  action  of  the  damper  in  detail,  assume  that  the  generator  speed 
momentarily  increases.  This  causes  a  difference  in  phase  of  the  generator  and 
converter  E.M.F.'s.  The  difference  in  the  instantaneous  E.M.F.'s  due  to  the 
difference  in  phase  will  cause  a  corrective  current  to  flow  in  the  circuit,  that  will 


FIG.  2. — Automatic  Regulators. 

distort  the  field  and  accelerate  the  converter  armature.  The  shifting  flux  cuts  the 
copper  grid  and  generates  in  it  eddy  currents,  which  retard  the  converter  armature. 
The  retarding  action  of  the  eddy  currents  occurs  only  while  the  relative  positions  of 
the  converter  and  generator  armatures  are  changing,  i.e.,  while  the  magnetic  flux  is 
moving  across  the  pole  face.  The  eddy  currents,  therefore,  do  not  act  as  a  constant 
opposing  force  to  the  corrective  currents,  but  as  a  true  damping  force,  becoming  zero 
whenever  the  generator  and  converter  armatures  revolve  exactly  in  synchronism. 


SUBSTATIONS.  301 

Induction  Regulator.  The  induction  regulator  consists  of  a  polyphase  transformer 
with  primary  movable  with  respect  to  the  secondary.  The  construction  of  core  and 
winding  resembles  that  of  an  induction  motor.  The  primary  is  connected  across 
and  the  secondary  in  series  with  the  line.  By  shifting  the  position  of  the  primary 
winding  of  the  regulator,  the  secondary  voltage  delivered  to  the  alternating  side  of 
the  converter  may  be  raised  or  lowered  without  opening  any  part  of  the  circuit,  and 
the  voltage  on  the  direct  current  side  thus  varied.  When  of  sufficient  size,  the  regu- 
lator may  be  operated  by  a  small  motor.  This  method  of  regulation  may  be  employed 
to  overcome  small  and  infrequent  fluctuations  in  the  line  voltage  in  lighting,  electro- 
lytic and  similar  service. 

Compounding.  It  is  generally  understood  that  there  is  a  certain  adjustment  of 
field  strength  which  gives  a  minimum  alternating  input  for  a  given  direct  current 
output,  and  that  an  overexcited  field  sets  up  a  leading  current  in  the  line,  while  an 
underexcited  field  causes  the  line  current  to  lag.  As  change  in  the  field  strength 
alone  cannot  appreciably  affect  the  direct  current  voltage,  the  ratio  between  the  two 
E.M.F.'s  remaining  practically  fixed,  the  only  way  to  vary  the  direct  potential  is  to 
vary  the  alternating  potential  at  the  collector  rings.  It  is,  however,  possible  by  a 
proper  proportion  of  series  excitation  and  the  provision  of  sufficient  inductance  in 
the  supply  line,  to  produce  a  change  in  the  voltage  at  the  collector  rings,  resulting  in 
a  corresponding  effect  at  the  direct  current  terminals.  The  conditions  for  rotary 
converter  compounding  are,  therefore,  a  series  winding  on  the  field  connected  to 
assist  the  shunt,  and  inductance  in  the  line  between  the  generator  and  converter. 
The  series  winding  of  a  rotary  converter  does  not  directly  increase  the  direct  current 
voltage,  as  in  a  direct  current  generator,  but  acts  indirectly  with  the  aid  of  inductance 
in  the  supply  circuit. 

Rotary  converters  which  are  compounded  to  give  a  constant  or  increasing  voltage 
with  increasing  load,  maintain  a  practically  uniform  voltage  at  the  generator  ter- 
minals, and  therefore  do  not  produce  the  drop  in  voltage  which  usually  occurs  when 
the  generator  load  increases.  This  enables  a  practically  constant  voltage  to  be 
maintained  on  other  circuits  supplied  by  the  same  generator,  independent  of  the 
variations  in  load  upon  the  rotary  converter.  Both  lighting  and  railway  loads  may 
thus  be  supplied  simultaneously  from  the  same  bus  bars,  provided  the  proper 
compensation  is  effected,  and  the  fluctuations  in  load  do  not  cause  an  appreciable 
variation  in  the  speed  of  the  generators. 

In  some  systems,  alternating  current  is  supplied  to  rotary  converters  'at  a  distance 
from  the  power  house,  while  other  converters,  located  in  the  power  house,  are  sup- 
plied with  current  from  the  same  generators.  If  the  converters  in  the  power  house 
are  to  be  compounded  to  give  a  rising  voltage  with  increase  of  load,  it  is  necessary  to 
provide  self-induction  either  in  transformers  or  in  choke  coils,  placed  between  the  bus 
bars  and  the  converter. 

Reactances.  To  enable  the  direct  current  voltage  to  be  altered  by  the  field  rheo- 
stat or  automatically  by  compounding,  which  calls  for  a  corresponding  change  of  the 
alternating  current  voltage,  a  phase  reactance-coil  is  provided  between  the  low-ten- 
sion windings  of  the  transformer  and  the  converter.  Without  such  a  reactance,  the 


302 


HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 


maintenance  of  the  same  voltage  at  full  load  as  at  no  load,  involves  excessive  leading 
and  lagging  currents,  and  consequently  excessive  heating  in  the  converter  armature, 
unless  the  resistance  drop  from  the  source  of  constant  potential  is  small,  or  the  natural 
reactance  of  the  circuit  is  unusually  high.  If  the  armature  field  is  weakened,  a 
lagging  current  is  set  up,  which  causes  a  drop  in  the  reactive  coil.  If  the  field  is 
strengthened,  a  leading  current  is  set  up  which  gives  a  rise  of  voltage  in  the  reactive 
coil.  Under  heavy  load,  the  series  field  of  a  compound  converter  tends  to  produce 
leading  currents,  which  tendency  is  practically  balanced  by  the  reactance,  improving 
the  power  factor  of  transformers,  lines  and  generators  when  loaded. 


FIG.  3. — Typical  Continental  Motor  Generator  Substation.     Vienna  Railway  System. 

Motor  Generators.  Motor  generator  sets  may  be  used  in  place  of  rotary  con- 
verters, if  the  line  voltage  is  not  too  high;  the  motor  of  the  set  may  be  directly  con- 
nected to  the  line,  thus  eliminating  transformers.  The  advantages  of  using  a  motor 
generator  are,  that  no  synchronizing  apparatus  is  necessary,  the  voltage  of  the  gen- 
erator bears  no  relation  to  that  of  the  supply,  same  as  in  a  converter,  and  it  may  be 
adjusted  through  a  wide  variation.  The  disturbance  known  as  "  hunting "  is 
unknown  in  the  motor  generator,  when  an  induction  motor  is  used  as  the  driver, 
and  no  skilled  attendants  are  necessary.  The  disadvantages  are,  that  the  efficiency 
is  from  4  to  7  per  cent  less  than  that  of  a  transformer-converter  set,  and  they  cost 


SUBSTATIONS. 


303 


more.  With  what  voltage  a  motor  generator  can  be  used  without  the  use  of  a  step- 
down  transformer,  depends  entirely  upon  the  design  of  the  motor.  The  accompanying 
illustrations  give  an  idea  of  motor  generator  sets  as  used  in  Europe  where  they  are 
most  extensively  employed.  Fig.  4  shows  the  interior  of  a  substation  at  Steghof, 
Switzerland;  each  motor  generator  consists  of  a  34O-K.W.,  265o-volt,  alternating 
current  motor,  coupled  to  a  30O-K.W.,  575-volt,  direct  current  generator,  running 
at  490  R.P.M. 

Frequency  Changers.     A  frequency  changer  differs  from  a  motor-generator  set  in 
the  following  respects:  The  driving  motor  must  be  a  synchronous  motor  and  the 


FIG.  4. — Motor  Generator  Sets.    Substation  "  Steghof,"  Switzerland. 

generator,  an  alternating  current  machine.  The  generator  has  more  or  less  pairs  of 
poles  than  the  motor,  depending  upon  the  frequency  desired.  Sometimes  an  induc- 
tion motor  is  substituted  in  place  of  the  generator  and  made  to  rotate  above  or  below 
its  rated  speed.  The  alternating  current  line  is  connected  to  the  rotor  of  the  motor, 
and  if  the  rotor  operates  above  its  normal  speed,  the  frequency  is  increased;  if  below, 
the  frequency  is  decreased. 

Frequency  changers  are  not  very  much  used;  however,  when  they  are  employed, 
they  are  used  in  plants  which  run  in  parallel  with  others  of  different  frequencies.  A 
notable  example  in  the  use  of  frequency  changers  is  in  Montreal,  Quebec.1 

1  Frequency  Changers  at  Montreal,  by  B.  A.  Behrend,  Electrical  World  and  Engineer,  Feb.  13,  1904. 


304 


HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 


"  The  City  of  Montreal,  Quebec,  obtains  electric  energy  for  power  and  lighting 
from  three  plants,  which  have  three  different  frequencies.  The  Chambly  power 
plant  supplies  alternating  current  at  66  cycles,  the  Lachine  Hydraulic  Land  & 
Power  Company  generates  alternating  current  at  60  cycles,  and  the  Shawinigan  Water 
&  Power  Company  generates  alternating  current  at  30  cycles.  Since  the  consolida- 
tion of  these  three  plants,  a  compromise  frequency  of  63  cycles  has  been  adopted. 

"  At  Shawinigan  Falls  there  are  installed  two  3750-]$.. W.  generators  operating 
at  180  revolutions  and  30  cycles,  and  generating  230x3  volts  two-phase.  By  means  of 
transformers,  the  two-phase  current  is  changed  to  three-phase  55,000  volts,  which  is 
transmitted  from  Shawinigan  to  Maisonneuve,  a  distance  of  85  miles.  In  the  sub- 
station at  Miasonneuve,  a  suburb  of  Montreal,  the  3O-cycle,  three-phase  current  is 
stepped  down  from  44,000  to  2300  volts.  The  long  distance  line  between  Shawini- 
gan Falls  and  Maisonneuve  is  operated  at  the  potential  of  55,000  volts  at  the  gener- 
ating end,  and  44,000  volts  at  the  receiving  end.  The  three-phase,  high  potential 
current  is  reduced  by  three  transformers  from  44,000  to  2300  volts. 

"  The  five  groups  of  frequency  changers  change  the  current  from  2300  volts 
three-phase  30  cycles  to  2300  volts  three-phase  60  cycles.  Fig.  5  is  the  3O-cycle  motor; 


FIG.  5. — Outline  of  io65~KW.  Frequency  Changers. 

the  machine  to  the  right  is  the  oo-cycle  generator;  the  exciter  shown  on  the  right  hand 
side  of  the  set  serves  as  a  starting  motor  and  also  excites  the  two  alternators.  The 
rating  of  each  set  is  1068  K.W.  at  2300  volts  60  cycles,  100  per  cent  power-factor,  or 
800  K.W.  at  75  per  cent  power-factor.  The  speed  of  the  frequency  changers  is  450 
revolutions,  the  motor  being  an  8-pole  machine,  the  generator  a  i6-pole  machine. 

"The  frequency  changers  are  started  from  the  exciters,  which  are  good  for  75  K.W. 
at  120  volts.  Although  the  excitation  of  each  machine  does  not  exceed  18  K.W. 
under  any  condition  of  load,  it  was  deemed  advisable  to  use  large  exciters  in  order 
to  facilitate  the  starting  of  these  sets,  as  at  the  moment  of  starting  the  current  taken 
is  quite  considerable.  A  3o-cycle  induction  motor  direct-connected  to  an  8o-K.W. 
direct-current  generator  is  used  for  the  starting  of  the  frequency  changers. 

"The  operation  in  multiple  of  frequency  changers  is  of  considerable  interest. 
Imagine  a  frequency  changer  to  be  in  operation  and  that  a  second  frequency  changer 


SUBSTATIONS. 


305 


is  to  be  connected  in  parallel  with  the  first.  Imagine  that  the  first  set  is  carrying 
full  load  and  that  the  second  set  is  to  divide  the  load  with  it. 

"The  motor  can  be  synchronized  in  the  usual  manner  by  adjusting  the  field 
current,  so  that  the  potential  difference  between  the  bus  bars  and  the  synchronous 
motor  vanishes.  If  the  generator  is  synchronized  in  the  same  way  it  is  not  possible 
to  put  a  load  on  the  machine.  If  the  field  current  of  the  generator  is  diminished  or 
increased  the  load  of  the  frequency  changer  remains  unaltered  and  the  effect  of 
changing  the  excitation  results  only  in  an  increase  of  the  cross  currents  between 
the  two  sets. 

"Now  then,  in  order  to  make  the  second  frequency  changer  divide  the  load  with 
the  first,  it  becomes  essential  to  abandon  the  usual  way  of  paralleling.  Let  it  be 
assumed  that  both  sets  are  in  operation  and  are  dividing  the  load  equally.  The 


T 


T 


I — v- 


T 


J/' 


I — *• 


i — #• — i 


FIG.  6. — Typical  Substation  Switch  Board  Panels,  i.  Incoming  Line  or  A.C.  Converter 
Panel.  2.  Outgoing  Line  Panel.  3.  D.C.  Converter  Panel.  4.  D.C.  Single  Circuit 
Feeder  Panel. 


saturation  curves  of  the  machines  being  the  same,  it  is  clear  that  the  exciting  currents 
of  the  machines  must  also  be  the  same  if  the  load  be  distributed  uniformly  between 
them.  As  juggling  the  field  currents  after  the  machine  has  been  thrown  in  parallel 
has  no  other  effect  than  to  increase  the  cross  currents,  it  is  evident  that  the  field 
currents  have  to  be  adjusted  properly  before  the  machines  are  thrown  in  parallel. 
Hence,  assume  the  first  set  in  operation  with  125  amperes  excitation  on  the  fields  of 
the  generator.  To  throw  the  second  set  in  parallel  with  the  first  set,  first  synchronize 
the  motor  of  the  second  set  and  then  make  the  excitation  of  the  generator  of  the 
second  set,  125  amperes.  The  bus  bar  voltage  on  which  the  first  set  is  operating 
is  2300  volts;  the  second  set  has  the  same  excitation  and  the  terminal  voltage  of  its 


306 


HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 


o 
fc 

a 
o 


C/3 


S 

a 

•~ 

SP 


bC 

c 

!S 

£ 


- 


SUBSTATIONS.  307 

generator  is,  therefore,  greater  than  the  bus  bar  voltage  on  which  the  machine  is  to 
operate. 

Assume  the  drop  of  the  machine  at  its  load  to  be  12  per  cent;  then  the 
generator  of  the  second  set  at  125  amperes  excitation  on  its  fields  will  generate  2580 
volts.  The  switches  must  be  closed  between  the  two  machines  at  these  unequal 
voltages  and  the  two  sets  will  pull  each  other  in  parallel  with  the  load  distributed 
equally  between  them." 

Switch  Gear.  The  switch  gear  is  similar  to  that  of  the  main  generating  station. 
Each  incoming  feeder  circuit  has  its  own  panel,  and  the  equipment  depends  some- 
what on  the  form  of  switch  adopted,  whether  hand  or  electric  operated.  Fig.  6 
shows  typical  substation  panels  one  and  two  for  alternating  current;  the  former,  for 
incoming  high  tension  lines,  having  a  lever  for  remote  control  automatically  tripped 
oil  switch,  and  one  ammeter;  the  latter,  for  low  tension  distribution,  having  a  three- 
pole,  automatically  tripped  switch  and  three  ammeters.  No.  3  is  the  main  con- 
verter panel,  having  a  circuit-breaker  with  overload  and  low  voltage  release,  one 
ammeTer,  one  field  rheostat,  a  potential  receptacle,  single-pole  main  switch,  a  double 
throw  station-lighting  switch,  and  the  bottom  panel  contains  a  recording  wattmeter. 
The  last  panel  is  a  direct  current  feeder  panel  equipped  with  an  overload  circuit- 
breaker,  ammeter,  main  switch,  lightning  arrester  and  choke  coil,  one  potential 
receptacle  by  which  the  feeder  voltage  may  be  determined  with  the  circuit-breaker 
open.  This  is  used  to  advantage  when  the  converters  are  started  up  on  the  direct 
current  side. 

The  high  and  low  tension  alternating  current  bus  bars  must  be  separated  if  such 
are  installed.  In  small  stations  the  transformers  are  directly  connected  without  the 
use  of  a  bus.  In  large  stations,  high  and  low  tension  bus  bars  are  placed  on  either 
side  of  the  transformers,  so  that  a  converter  may  be  operated  without  its  own 
transformer  when  necessary. 

Separate  converters  must  be  kept  for  lighting  and  railroad  work,  which  means 
two  direct  current  bus  bar  systems.  They  must,  however,  be  interconnected  that 
the  converters  can  supply  either  systems. 

What  previously  has  been  said  under  switchboards  regarding  flexibility,  etc., 
applies  also  to  substation  equipment. 

BIBLIOGRAPHY. 

TRANSFORMERS  FOR  SINGLE  AND  MULTIPHASE  CURRENTS.    G.  Kapp.     1906. 

THE  ALTERNATING  CURRENT  TRANSFORMER.    F.  G.  Baum.     1903. 

THE  ALTERNATING  CURRENT  TRANSFORMER  IN  THEORY  AND  PRACTICE.     J.  A.  Fleming.     1900. 

PRINCIPLES  OF  THE  TRANSFORMER.    F.  Bedell.     1908. 

THE  SERIES  TRANSFORMER.     E.  S.  Harrar.     Electrical  World,  May  16,  1908. 

THE  CHOICE  OF  TRANSFORMERS  FOR  CENTRAL  STATIONS.    L.  A.  Sterrett.    Electrical  World,  May  2, 

1908. 
THE  CENTRAL  STATION  DISTRIBUTING  SYSTEM.    H.  B.  Gear  and  P.  F.  Williams.     Electrical  Age, 

February,  1908. 
SOME  FEATURES  OF  EUROPEAN  HIGH  TENSION  PRACTICE.    Frank  Koester.    Electrical  Age,  December, 

1908. 


308  HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 

THE  DETERMINATION  OF  THE  ECONOMIC  LOCATION  OF  SUB-STATIONS  IN  ELECTRIC  RAILWAYS.    Gerard 

B.  Werner.     Proc.  Am.  Inst.  E.  E.,  May,  1908. 

RECEIVING  STATION  OPERATED  FROM  HIGH-TENSION  TRANSMISSION  LINE.    Electrical  Age,  July,  1908. 
INSTRUCTIONS  TO  OPERATORS  IN  RAILWAY  CONVERTER  SUB-STATIONS.     J.  E.  Woodbridge.    Electric 

Railway  Journal,  June  13,  1908. 
PROTECTION  OF  THE  INTERNAL  INSULATION  OF  A  STATIC  TRANSFORMER  AGAINST  HIGH  FREQUENCY 

STRAINS.    W.  S.  Moody.    Proc.  Am.  Inst.  E.  E.,  May,  1907. 
RELATIVE  MERITS  OF  THREE-PHASE  AND  ONE-PHASE  TRANSFORMERS.     H.  W.  Tobey.    Proc.  Am. 

Inst.  E.  E.,  April,  1907. 
RELATIVE  ADVANTAGES  OF  ONE-PHASE  AND  THREE-PHASE  TRANSFORMERS.     J.  S.  Peck.    Proc.  Am. 

Inst.  E.  E.,  April,  1907. 
FORCED  OIL  AND  FORCED  WATER  CIRCULATION  FOR  COOLING  OIL  INSULATED  TRANSFORMERS.    C.  C. 

Chesney.    Proc.  Am.  Inst.  E.  E.,  April,  1907. 


A.E.&M 

UNIV.  OF  C 


CHAPTER  X. 
LINE   PROTECTION. 

LIGHTNING    ARRESTERS. 

Purpose.  To  guard  against  interruption  of  service  of  the  generating  plant  or 
substation,  the  electrical  apparatus  of  same  must  be  protected,  particularly  against 
atmospheric  discharges.  This  is  done  by  providing  the  transmission  system  with 
lightning  arresters  or  some  form  of  grounding  device.  The  function  of  same  is  to 
act  as  a  relief  vent. 

Various  sources  of  disturbances  (particularly  where  the  transmission  line  runs 
through  sections  of  country  of  different  altitudes),  the  chief  of  which  is  lightning, 
causing  surges  and  oscillations  in  the  circuit  of  such  frequency  and  high  potential 
as  will  endanger  the  apparatus  in  the  generating  plant,  substation  or  probably  both. 

Lightning  Discharges.  Lightning,  as  commonly  understood,  means  the  electric 
discharges  from  cloud  to  ground,  or  from  cloud  to  cloud,  but  the  word  "  lightning  " 
as  applied  to  electric  circuits,  means  much  more  than  this.  It  includes,  besides  the 
lightning  referred  to,  disturbances  due  to  static  unbalancing  of  the  circuit  and  surges, 
that  is,  disturbances  in  the  flow  of  generated  power,  brought  about  by  various  causes 
and  depending  for  their  energy  on  the  power  of  the  generating  system.  A  very  small 
per  cent  of  these  electrical  disturbances  results  from  direct  strokes,  the  far  greater 
number  resulting  from  induction  by  charged  clouds  suddenly  discharging  or  per- 
haps from  the  static  charges  collected  from  rain,  snow  or  fog  drifting  across  the  line. 

Regardless  of  their  source  all  static  disturbances  on  transmission  lines  are  charac- 
terized by  abnormal  potentials  and  abnormal  frequencies. 

Principle  of  Arresters.  The  lightning  arrester  must  permit  sufficient  freedom 
of  escape  of  the  charge  from  transmission  lines  so  as  to  limit  their  potential  to  a  safe 
value.  To  do  this,  a  vent  is  required  which  will  permit  a  very  large  flow  of  current 
when  the  potential  is  above  a  certain  value,  but  which  will  suppress  this  flow  of  cur- 
rent quickly,  quietly,  and  completely  as  soon  as  the  potential  has  resumed  a  normal 
value.  In  other  words,  the  arrester  must  permit  the  escape  of  the  abnormal  surge, 
but  should  preferably  take  no  current  whatever  and  consequently  cause  no  additional 
disturbance  or  drop  in  voltage. 

In  general,  a  lightning  arrester  is  made  up  of  three  elements,  as  follows:  An  air 
gap,  a  current  limiting  element  and  an  arc  suppressing  device.  Two  of  these  ele- 
ments are  always  present,  and  usually  the  other  is  combined  in  some  form  with  the 
other  two.  The  air-gap  holds  the  voltage  ordinarily,  but  is  broken  over  by  any  great 
excess  potential,  thus  permitting  current  to  flow.  The  current  limiting  element 

3°9 


310  HYDROELECTRIC    DEVELOPMENTS    AND    ENGINEERING. 


FIG.  i. — Siemens-Schuckert  Horn  Lightning  Arrester.     Showing  Principle  of  Action. 


LINE   PROTECTION. 


usually  appears  in  the  form  of  a  series  resistance  of  some  kind  which  limits  the  power 
current  to  a  reasonable  value.  The  arc-suppressing  device  is  provided  by  some 
modification  of  the  air-gap,  and  may  consist  of  a  magnetic  blow-out,  a  mechanical 
arrangement  by  which  the  length  of  the  gap  is  increased  until  the  arc  breaks  (horn 
type),  or  non-arc-metal  gaps  consisting  of  a  number  of  small  cylinders  with  the 
proper  spacing  between  them. 

Horn  Lightning  Arresters.  In  Continental  Europe,  where  it  originated,  the  horn 
type  lightning  arrester  has  been  extensively  used  since  the  early  stages  of  electric 
transmission.  It  is  based  on  the  principle  that  a  short-circuited  arc  once  started  at 
the  narrow  gap  between  the  horns,  the  heat  of  the  arc 
will  cause  it  to  travel  upwards  along  the  members  of 
the  horn  and  break  by  reason  of  its  attenuation.  In 
some  recent  practice,  auxiliary  apparatus  is  used  in 
connection  with  it,  such  as  water  flow  grounders,  oil 
resistances,  choke  coils,  relays,  condensers,  etc. 

Fig.  2  shows  a  Siemens-Schuckert  Relay  Horn  Light- 
ning Arrester  with  condensers,  Tesla  transformer, 
rheostat,  and  automatic  blow-out,  etc.  The  horns  are 
placed  3  to  4  mm.  apart,  which  is  the  lowest  practical 
setting,  because  dust  or  other  particles  may  collect  and 
cause  it  to  discharge  when  set  lower.  The  gap  of  3  to 
4  mm.  will  cause  the  arrester  to  discharge  under  ordi- 
nary operating  conditions  at  8000  volts,  but  with  the 
use  of  the  auxiliary  apparatus,  it  will  discharge  at  3000 
volts  and  lower  without  changing  the  setting  of  the 
horns.  This  is  accomplished  by  the  discharge  of  an 
auxiliary  gap  set  off  by  two  condensers;  the  auxiliary 

discharge  causes  high  frequencies  to  be  set  up  in  the 
rr,    i  f  ,.  ,  ,,  .  T,     ,,  . 

Tesla  transformer  which  starts  the  mam  gap.     By  this 

means   the   main  gap  can  be  set   to  several  times  the 


3.  2.  —  Siemens-Schuckert 
Horn  Gaps  with  Micro- 
metric  Setting. 


opening  otherwise  required  for  breakdown  at  2000  or  3000  volts.  Fig.  3  shows  the 
arrangement  of  six  such  arresters  connected  to  an  oil  resistor.  Three  of  the 
arresters  are  connected  in  "  Y  "  to  relieve  the  line  of  lightning  discharges  and  three 
are  connected  in  delta  between  phases  to  relieve  one  another  of  unbalancing 
effects. 

The  American  type  of  horn  lightning  arresters  is  usually  built  on  a  large  scale  and 
preferably  installed  out  of  doors.  Fig.  4  shows  such  an  arrester  as  installed  by  the 
American  River  Electric  Company,  California.  They  are  installed  on  the  40,000- 
volt  transmission  line,  and  are  made  of  galvanized  iron  gas-pipe  mounted  on  insu- 
lators on  a  pole  construction;  the  gap  is  2.25  inches.  The  horns  are  grounded  through 
a  25-gallon  water  tank  with  a  film  of  oil  on  top  to  keep  down  evaporation.  Expe- 
rience has  proved  that  pure  water  in  the  tank  gives  better  satisfaction  than  water  with 
salt.  The  company  reports:  "  In  one  instance  they  discharged  several  times  in  suc- 
cession, the  arc  traveling  halfway  up  before  breaking.  Every  discharge  had  the  same 


312  HYDROELECTRIC    DEVELOPMENTS    AND    ENGINEERING. 


FIG.  3.— Application  of  Siemens-Schuckert  Lightning  Arresters  with  Micrometric  Setting, 

and  Oil  Rheostat. 


LINE  PROTECTION. 


313 


effect  as  a  temporary  short-circuit,  causing  the  voltmeter  to  swing  entirely  across  the 
scale,  and  the  lights  to  dim  to  perhaps  half  candle  power.  We  have  had  no  trouble 
from  these  arresters,  no  damage  done  by  lightning,  and  consider  the  arrester  as  satis- 
factory for  high  voltage  as  any  now  in  use." 


To  Line 


FIG.  4. — Construction  of  a  Horn  Type  Arrester,        FIG.  5. — Curve  Showing  Setting  of  Horn 
American  River  Electric  Company.  Gaps. 

Horn-Gap  Setting.  In  Fig.  5  is  shown  a  curve  which  gives  the  proper  gap-lengths 
for  horn-gaps  when  used  on  certain  voltages.  According  to  American  ideas,  horn- 
gaps  should  not  be  used  for  potentials  lower  than  13,500  volts,  since  the  gap  is  so  small 


FIG.  6. — Protection  of  a  Combined  Overhead    FIG.  7. — Protection  of  a  Combined  Overhead 
and    Underground     Line,    Using    Oil-  and    Underground    Transmission    Line, 

Immersed  Choke  Coils.  *Using    Horn    Gaps    and    Oil-Immersed 

Resistances. 

that  the  arc  will  not  rise  properly  and  break.  Some  latitude  is  allowable  in  the  setting 
of  the  horn-gaps.  The  gap  must  be  so  set  that  small  arcs  will  not  strike  back  and 
rise  again  repeatedly. 


314  HYDROELECTRIC    DEVELOPMENTS    AND   ENGINEERING. 


FIG.  8. — Scheme  of  Station  Protection  by      FIG.  9. — Arrangement  of  Protecting  Apparatus 
Torchio.  of  3ooo-volt  Circuit  as  Proposed  by  Gola. 


FIG.  10. — Flat  Choke  Coil. 


FIG.  ii. — Hour  Glass  Type  of  Choke  Coil. 


LINE   PROTECTION. 


315 


Choke  Coils.  Choke  coils  are  installed  to  take  care  of  surges  in  the  line  and  are 
always  used  in  connection  with  the  various  kinds  of  lightning  protective  devices. 
The  advantages  of  using  a  choke  coil  are,  as  there  is  normally  no  voltage  between 
the  turns,  and  there  is  no  tendency  to  hold  a  short-circuit  in  case  of  a  surface  momen- 
tary discharge,  it  pc'rmits  of  a  cheapor  transformer  construction. 

They  are  made  in  various  forms,  such  as  flat  copper  strips  wound  in  spiral,  copper 
wire  wound  spirally  in  the  form  of  an  hour-glass,  or  in  cylindrical  spiral  form.  In 
most  forms  the  turns  are  insulated  from  one  another. 

Multigap  Arresters.  Of  the  various  makes  of  multigap  lightning  arresters,  the 
differences  between  them  amount  to  but  little.  They  are  built  to  operate  on  the 
same  principles,  which  are  as  follows:  The  greater  the  value  of  the  dynamic  current, 
the  greater  the  number  of  gaps  required  to  extinguish  the  arc.  Any  arc  is  unstable 


GOOOO  Vtf(9  JOOOO  Volts 

FIGS.  12  and  13. — Three  Phase  Multigap  Lightning  Arresters,  General  Electric  Company. 

and  can  be  extinguished  by  placing  a  properly  proportioned  resistance  in  parallel 
with  it.  Further,  the  higher  the  frequency  of  the  lightning  oscillations,  the  more 
readily  will  the  multigap  respond  to  the  potential. 

Being  made  up  of  units,  the  multigap  arrester  can  be  built  for  all  commercial 
voltages.  Those  used  on  circuits  below  6000  volts  are  classified  as  low  tension,  and 
those  above,  as  high  tension  arresters. 

Action  of  Multigap  Arrester.  The  essential  elements  of  this  arrester  are  a  number 
of  cylinders  spaced  with  a  small  air-gap  between  them,  and  placed  between  line  and 
ground,  and  between  line  and  line.  In  operation,  the  multigap  arrester  discharges 
at  a  much  lower  voltage  than  would  a  single  gap  having  a  length  equal  to  the  sum 
of  the  small  gaps. 

In  explaining  the  action  of  multigaps,  there  are  three  things  to  take  into  considera- 
tion; the  transmission  of  the  static  stress  along  the  line  of  the  cylinders;  the  sparking 
of  the  gaps;  the  action  and  duration  of  the  dynamic  current  which  follows  the  spark, 


HYDROELECTRIC    DEVELOPMENTS    AND   ENGINEERING. 


and  the  extinguishment  of  the  arc.     A  spark  may  be  defined  as  conduction  of  elec- 
tricity by  the  air,  and  an  arc  as  conduction  of  electricity  by  vapor  of  the  electrode. 

The  cylinders  of  the  multigap  arrester  act  like  plates  of  condensers  in  series. 
This  condenser  function  is  the  essential  feature  of  its  operation.  When  a  static 
stress  is  applied  to  a  series  of  cylinders  between  line  and  ground,  the  stress  is  instantly 
carried  from  end  to  end.  If  the  top  cylinder  is  positive  it  will  attract  a  negative 

charge  on  the  face  of  the 
adjacent  cylinder  and 
repel  an  equal  positive 
charge  to  the  opposite 
face,  and  so  on  down  the 
entire  row. 

The  second  cylinder 
has  a  definite  capacity 
relative  to  the  third  and 
also  to  the  ground;  con- 
sequently the  charge 
induced  on  the  third 
cylinder  will  be  less  than 
on  the  second,  due  to 
the  fact  that  only  part  of 
the  positive  charge  on  the 
second  cylinder  induces 
negative  electricity  on 
the  third,  while  the  rest 
of  the  charge  induces 
negative  electricity  to  the 
ground.  Each  succes- 
sive cylinder,  counting 
from  the  top  of  the 
arrester,  wrill  have  a 
slightly  less  charge  of 
electricity  than  the  pre- 
ceding one.  This  condition  has  been  expressed  as  "a  steeper  potential  gradient 
near  the  line." 

The  quantity  of  electricity  induced  on  the  second  cylinder  is  greater  than  on  any 
lower  cylinder,  and  its  gap  has  a  greater  potential  strain  across  it.  When  the  potential 
across  the  first  gap  is  sufficient  to  spark,  the  second  cylinder  is  charged  to  line  poten- 
tial and  the  second  gap  receives  the  static  stress  and  breaks  down.  The  successive 
action  is  similar  to  overturning  a  row  of  nine-pins  by  pushing  the  first  pin  against  the 
second.  This  phenomenon  explains  why  a  given  length  of  air-gap  concentrated  in 
one  gap  requires  more  potential  to  spark  across  it  than  the  same  total  length  made 
up  of  a  row  of  multigaps.  As  the  spark  crosses  each  successive  gap,  the  potential 
gradient  along  the  remainder  readjusts  itself. 


FIG.  14. — Graded  Shunt  Resistance,  Multigap  Lightning 
Arrester,  General  Electric  Company. 


LINE  PROTECTION. 


317 


When  the  sparks  extend  across  all  the  gaps,  the  dynamic  current  will  follow  if, 
at  that  instant,  the  dynamic  potential  is  sufficient.  On  account  of  the  relatively 
greater  current  of  the  dynamic  flow,  the  distribution  of  potential  along  the  gaps 
becomes  equal,  and  has  the  value  necessary  to  maintain  the  dynamic  current  arc 
on  a  gap.  The  dynamic  current  continues  to  flow  until  the  potential  of  the  generator 
passes  through  zero  to  the  next  half  cycle,  when  the  arc-extinguishing  quality  of  the 
metal  cylinders  comes  into  action.  The  alloy  contains  a  metal  of  low  boiling  point 
which  prevents  the  reversal  of  the  dynamic  current.  It  is  a  rectifying  effect,  and 
before  the  potential  again  reverses,  the  arc  vapor  in  the  gaps  has  cooled  to  a  non- 
conducting state. 

Installation  of  Multigap  Arresters.  The  multigap  arresters  may  be  installed  on 
delta  connected  and  also  on  "Y"  connected  circuits,  with  the  neutral  grounded  or 
ungrounded.  The  difference  lies  in  the  use  of  a  fourth  arrester  leg  between  the 
multiplex  connection  and  ground  on  underground  systems. 

The  reason  for  introducing  the  fourth  leg  is  evident,  for  if  one  leg  becomes 
accidentally  grounded,  the  full  line  potential  would  be  thrown  across  one  leg  if  the 
fourth  or  ground  leg  were  not  present.  On  a  "  Y"  system  with  a  grounded  neutral, 
the  accidentally  grounded  phase  causes  a  short-circuit  of  the  phase  and  the  arrester  is 
relieved  of  the  stress  by  the  tipping  of  the  circuit  breaker.  Briefly  stated,  the  fourth 
or  grounded  leg  of  the  arrester  is  used  when,  for  any  reason,  the  system  could  be 
operated  even  for  a  short  time,  with  one  phase  grounded.  In,  protecting  2-phase 
4-wire  circuits,  two  single  phase,  multiplex  connected  arresters  are  used;  when 
protecting  2-phase  3-wire  circuits,  two  single  phase  arresters  are  connected  in  between 
the  outside  leg  and  the  common  leg,  no  multiplex  cross  connection  being  between 
the  outside  legs.  As  much  wall  space  as  possible  must  be  provided,  and  plenty  of 
room  in  front  must  be  left  for  the  operator.  The  following  minimum  separation 
distances,  recommended  by  the  General  Electric  Company  for  the  past  few  years, 
have  proved  entirely  satisfactory. 

TABLE    I.  —  GIVING    PROPER    SPACE    BETWEEN  ARRESTERS. 


Volts. 

Distance  between 
live  parts  of 
adjacent  phases. 

Minimum  distance 
between  centers.1 

Inches. 

Inches. 

6,600 

8 

28 

IO,OOO 

8 

28 

12,500 

8 

33 

15,000 

10 

35 

2O,ooo 

12 

37 

25,000 

IS 

48 

30,000 

22 

52 

35'°°° 

26 

56 

40,000 

28 

62 

45,000 

32 

67 

50,000 

36 

72 

60,000 

40 

78 

1  If  barriers  are  used,  the  width  of  barriers  should  be  added  to  distances  given. 


HYDROELECTRIC    DEVELOPMENTS    AND    ENGINEERING. 


It  is  advisable  to  install  arresters  in  a  dry  place,  and  before  assembling  them,  the 
wooden  supports,  insulators,  etc.,  must  be  thoroughly  dried  of  all  moisture  which 
may  have  collected. 

Fluid  Arresters.  There  are  two  different  kinds  of  fluid  arresters  in  American 
practice.  In  one,  the  components  are  submerged  in  oil  in  a  steel  tank,  and  known 
as  Aluminum  Arresters  (General  Electric  Company) :  in  the  other,  the  components 
are  incased  in  an  empty  porcelain  jar,  and  known  as  the  Electrolytic  Arrester 
(Westinghouse  Electric  and  Manufacturing  Company).  The  principle  of  both  is 

practically  the  same.  It  consists  of  a  series  of  concentric 
aluminum  pans,  placed  one  above  the  other,  separated  by 
an  electrolyte,  usually  a  borax  solution. 

Experiments  have  been  made  for  a  number  of  years 
with  a  film,  which  may  be  formed  on  aluminum  plates, 
when  treated  with  certain  electrolytes.  This  film  being 
very  thin,  that  is,  comparable  in  thickness  with  a  wave 
length  of  light,  its  electrostatic  capacity  as  a  condenser 
is  very  great.  If  the  electromotive  force  is  constant, 
only  leakage  current  passes  through,  but  if  it  is  alter- 
nating, there  is  a  leakage  and  a  charging  or  condenser 
current  superimposed. 

It  was  discovered  that  this  film  has  a  very  desirable 
characteristic  for  lightning  arrester  purposes,  in  that  it 
has  an  apparent  resistance  of  a  very  high  value  when 
moderate  voltages  are  impressed  upon  it.  When  the 
voltage  or  pressure  reaches  a  certain  value,  however, 
this  film  breaks  down  in  myriads  of  minute  punctures 
making  almost  a  short  circuit  for  these  higher  voltages. 
As  soon,  however,  as  the  voltage  is  reduced  again,  the 
minute  punctures  seal  up  at  once,  and  original  high 
resistance  reasserts  itself.  It  may  be  seen  that  for  elec- 
trical pressure,  this  action  is  exactly  the  same  as  that  of  a 
safety  valve  on  a  boiler. 

In  the  aluminum  arrester,  each  cell  is  designed  to 
operate  normally  at  300  volts  with  a  very  small  leakage  current,  and  with  a  perma- 
nent critical  value  of  420  volts,  that  is,  the  voltage  at  which  the  film  opens  and 
allows  a  free  and  heavy  discharge  is  420,  and  the  permanent  critical  value  is  thus 
40  per  cent  above  the  normal  operating  voltage. 

If  the  potential  rises  to  any  value  greater  than  300  and  less  than  420  volts,  a  tem- 
porary critical  value  is  reached  and  the  film  allows  the  arrester  to  discharge  for  a 
short  time.  A  thicker  film  is  soon  formed  and  the  leakage  current  is  decreased  to  a 
small  amount.  When  the  line  potential  again  becomes  normal,  this  extra  thickness 
of  the  film  gradually  dissolves.  If  the  voltage  continues  to  rise,  this  process  of  form- 
ing a  temporary  critical  film  continues  until  the  permanent  critical  value,  420  volts, 
is  reached,  when  the  cells  discharge  freely,  allowing  a  heavy  rush  of  current.  The 


FIG.  15. —  General  Electric 
Company's  Aluminum 
Lightning  Arrester. 


LINE  PROTECTION. 


319 


700 
.600 

soo 


Ifpo 


VOLT-AMPERE:  CHARACTER/STIC 


FIG.  16. — Discharge  Rate  Above  Permanent  Critical  Value. 


/•MO 

[360 

$230 

eo 

140 

i 

Uf 

Vot-T-AMPEffc  CHARA 
ALUMJNUM  UGHTN/N 

CTER/5T/C 

GAffR£STE> 

_ 

>           ,O/          .OS         ^7J         ^*        .OS         .06         -<77        ,.O0         ^>          ^O          .// 
Amperes 

Fig.  17. — Characteristic  Curve  at  Permanent  Critical  Value  of  General 
Electric  Aluminum  Arrester. 


For  Delta  or  Ungrounded  F  System.  For  Grounded  Neutral  System. 

FIGS.  18  and  19. — Arrangement  of  General  Electric  Company's  Arresters.     In  the  Installation 

the  Bases  of  the  Horn  Gaps  are,  of  course,  Horizontal. 


HYDROELECTRIC    DEVELOPMENTS   AND    ENGINEERING. 


plate  area  of  the  cells  is  sufficient  to  discharge  a  quantity  of  electricity  many  times 
greater  than  that  which  would  be  liberated  by  an  ordinary  induced  lightning 
stroke. 

The  upper  cut  in  Fig.  16  is  a  volt-ampere  curve  showing  the  characteristics  of  a 
film  which  has  been  formed  up  to  its  permanent  critical  value ;  the  lower  (drawn  to  a 


FIG.  20. — Outside  Installation  of  Westinghouse  Electrolytic  Lightning  Arresters. 

different  scale)  shows  the  discharge  rate  above  the  permanent  critical  value.  Suffi- 
cient cells  are  placed  in  series  on  circuits  of  any  given  voltage  to  allow  a  normal  volt- 
age of  300  volts  per  cell. 

The  arresters  are  connected  permanently  between  line  and  ground.     A  multi- 
gap  or  horn-gap,  set  at  a  suitable  value  above  line  potential,  is  inserted  in  series,  and 


LINE  PROTECTIONS. 


321 


FIG.  21. — Westinghouse  Electrolytic        FIG.  22. — Horn  Lightning  Arresters  with  Water 
Lightning  Arrester.  Flow  Grounder  at  Substation  Steghof,  Switzerland. 


FIG.  23. — Oerlikon  Water  Flow  Grounder. 


322 


HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 


FlG.  24. — 5o,ooo-volt  Alioth  Waterflow  Grounder  at 
Step-up  Station,  Piattamala,  Italy. 


FIG.  25. — Bank  of  Horn  Gaps,  Choke  Coils,  and  Water  Flow  Grounders 
installed  at  the  Vandoise  Motor  Power  Company's  Plant  at  Lakes  of 
Joux  and  Orbe,  Switzerland. 


LINE   PROTECTIONS. 


323 


xawoovo 


TO    TI-U9    ^O//VT  • 


prevents  the  arrester  from  being  subjected  continuously  to  the  line  voltage.  In  this 
way  leakage  is  prevented  during  normal  operation,  and  a  longer  life  is  assured. 
The  accompanying  illustrations  show  the  application  of  these  types  of  lightning 
arresters. 

Frequently  the  horn  arrester  is  connected  to  water  flow  grounders.  Fig.  22  shows 
such  an  arrester  as  installed  by  the  Oerlikon  Company,  in  connection  with  a  27,000- 
volt  transmission  line.  The  grounding  device  consists  of  a  pair  of  glass  tubes  through 
which  water  is  continuously  flowing. 
Another  arrangement  of  a  water  flow 
grounder  as  installed  by  The  Alioth 
Company,  in  connection  with  the  50,000- 
volt  Swiss-Italian  transmission  system,  is 
seen  in  Fig.  24.  It  has  been  installed  in 
addition  to  horn-lightning  arresters  and 
choke  coils,  to  take  care  of  light  surges  in 
the  line  and  to  maintain  uniform  line 
pressure.  This  apparatus  consists  of  a 
nozzle  or  jet  of  water  (from  a  spring), 
playing  against  a  baffle  plate  connected 
to  the  line.  The  stream  of  water  is  three- 
eighths  of  an  inch  in  diameter,  28  inches 
high,  and  allows  a  leakage  of  o.i  ampere. 
Ammeters  are  inserted  in  the  line  connec- 
tion to  detect  failures  in  grounding. 

Water-flow  grounders,  in  different  forms, 
have  been  used  successfully  for  a  number 
of  years  on  the  Continent  of  Europe. 
However,  in  America  its  use  has  not  been 
advocated,  for  the  reason  that  the  assumption  of  the  failure  of  water  supply  points  out 
that  the  apparatus  is  inefficient.  This  argument  is  not  quite  justifiable,  as  the  water 
may  be  drawn  from  the  same  supply  as  the  turbines,  and  in  substations,  usually  located 
in  or  near  cities,  water  from  the  city  mains  can  be  used.  It  is  the  practice  in  Euro- 
pean countries  to  make  use  of  the  water  which  circulates  through  the  cooling  coils 
in  the  oil  transformers.  Further,  the  water  from  nearby  springs  is  oftentimes 
available. 

Location  of  Arresters.  The  main  generating  station  and  all  substations  must  be 
equipped  with  lightning  arresters.  Practice  of  recent  years  shows  that  it  is  good 
policy  to  install  more  than  one  form  of  arrester,  for  instance,  a  combination  of  multi- 
gap  and  horn  type  for  direct  lightning  strokes;  choke  coils  and  fluid  arresters  to  take 
care  of  slight  atmospheric  discharges  and  surges. 

Some  power  plants  are  equipped  with  all  four  of  the  above-mentioned  forms,  for 
example,  the  Ontario  Power  Company,  which  has  the  electrolytic  form  of  fluid 
arrester,  and  gaps  of  the  different  horns  set  for  various  voltages.  In  a  recently  installed 
7000/50,000- volt  transformer  station  at  Piattamala,  Italy,  the  station  protection  is  as 


FIG.  26. — Lightning  Rod. 


324  HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 

follows:  Flat  choke  coils  are  placed  on  both  sides  of  the  transformers  in  connection 
with  horn  lightning  arresters  provided  with  water  rheostats;  for  taking  up  lighter 
static  and  atmospheric  discharges,  cylindrical  choke  coils  with  non-inductive  resist- 
ances are  provided.  Finally,  as  all  surges  will  create  more  or  less  variation  in  pres- 
sure, water  jet  grounders  are  installed  to  maintain  uniform  pressure. 

The  location  of  lightning  protection  devices  is  a  matter  of  opinion.  In  American 
practice,  the  choke  coils  and  multigap  arresters  are  located  inside  the  station,  while 
the  fluid  and  horn-gap  arresters  are  outdoors.  In  Europe,  the  practice  is  to  locate 
all  the  lightning  protection  apparatus  inside  of  the  stations,  with  exception  of  those  on 
the  line.  Even  these  are  sometimes  placed  in  section  houses. 

The  transmission  line  itself  must  be  protected  against  lightning  either  by  horn- 
lightning  arresters  at  frequent  intervals  (about  2  or  3  miles),  or  by  the  overhead  guard 
wire.  The  latter  is  more  frequently  used  on  wooded  pole  line  construction.  Where 
no  guard  wire  is  used  on  wooden  pole  lines,  the  individual  poles  must  be  provided 
with  a  lightning  rod  extending  some  ten  to  twelve  inches  above  the  top,  sometimes 
fastened  to  an  iron  pole-cap. 

Guard  wires,  and  all  lightning  arresters,  must  be  well  grounded  by  a  copper  wire 
having  a  short  and  straight  run  to  ground. 

The  end  may  be  wound  in  a  coil  or  connected  to  a  copper  plate  buried  in  the  ground. 
Flat  copper  strip  is  sometimes  used  in  place  of  copper  wire.  The  efficiency  of  the 
grounding  wire  is  increased  if  the  earth  plate  is  buried  in  moist  ground. 

BIBLIOGRAPHY. 

LlGHTNING-RODS  AND  GROUNDED  CABLES  AS  A  MEANS  OF  PROTECTING  TRANSMISSION  LlNES  AGAINST 

LIGHTNING.    Norman  Rowe.    Proc.  Am.  Inst.  E.  E.,  May,  1907. 
PRACTICAL  TESTING  OF  COMMERCIAL  LIGHTNING  ARRESTERS.    P.  H.  Thomas.  Proc.  Am.  Inst.  E.  E., 

June,  1907. 

A  PROPOSED  LIGHTNING  ARRESTER  TEST.    N.  J.  Neall.    Proc.  Ant.  Inst.  E.  E  ,  June,  1907. 
PROTECTIVE  APPARATUS  ENGINEERING.    E.  E.  F.  Creighton.    Proc.  Am.  Inst.  E.  E.,  June,  1907. 
PROTECTION  AGAINST  LIGHTNING,  AND  THE  MULTIGAP  LIGHTNING  ARRESTER.    D.  B.  Rushmore  and 

D.  Dubois.     Proc.  Am.  Inst.  E.  E.,  April,  1907. 
NEW  PRINCIPLES  IN  THE  DESIGN  OF  LIGHTNING  ARRESTERS.  E.  E.  F.  Creighton.  Proc.  Am.  Inst.  E  E., 

1907. 
SOME  FEATURES  OF  EUROPEAN  HIGH-TENSION  PRACTICE.    Frank  Koester.     Electrical  Age,  December, 

1908. 


PART  III. 

(APPENDIX.) 

MODERN  AMERICAN  AND  EUROPEAN  HYDROELECTRIC 
DEVELOPMENTS. 


A.E.& 

UNIV.  o 


APPENDIX. 

TYPICAL    HYDROELECTRIC    PLANTS. 


THE   POWER   PLANT  AND   TRANSMISSION   SYSTEM   OF  THE   ONTARIO   POWER 

COMPANY. 

ACCORDING  to  Zoelly,  in  a  paper  before  the  Engineering  and  Architectural  Society 
of  Zurich,  Switzerland,1  there  is  no  accurate  data  on  the  flow  of  water  over  Niagara 
Falls;  it  is  estimated  that  the  flow  is  one  hundred  million  cubic  meters  per  minute 
(three  thousand  five  hundred  and  thirty  million  cubic  feet).  This  is  sufficient  to 
develop  16,800,000  HP.,  or,  figuring  on  an  efficiency  of  75  per  cent,  12,600,000  HP.2 
Although  this  enormous  amount  of  power  is  available,  and  in  spite  of  the  number  of 
large  plants  already  erected,  only  a  small  percentage  of  the  water  is  utilized. 

Since  1890,  when  the  International  Power  Commission  met  to  decide  upon  the 
utilization  of  the  water  of  Niagara,  great  progress  has  been  made  in  water-power 
development.  On  April  4,  1895,  the  first  5ooo-HP.  turbine  of  the  Niagara  Falls  Power 
Company  was  set  in  motion.  The  many  plants  now  located  around  Niagara  Falls 
give  ample  proof  of  the  success  of  this  first  installation,  especially  as  three  other 
Niagara  plants  have  been  built  on  the  same  lines.  It  will  be  noticed  by  studying  the 
accompanying  drawing,  that  on  the  American  side  are  located,  besides  several  small, 
four  large  installations;  two  above  the  rapids,  and  two  below  the  falls  in  the  gorge. 
The  law  of  the  New  York  State  Reservation,  1885,  stipulated  that  the  big  power 
developments  had  to  be  one  mile  away  from  the  Falls.  On  the  Canadian  side, 
conditions  were  different;  the  whole  of  Victoria  Park  was  thrown  open  wide  to  the 
development  of  power  from  the  Horse-Shoe  Falls. 

Starting  on  the  American  side,  above  the  Falls,  are  located  power  houses  Nos.  i  and 
2  of  the  Niagara  Falls  Power  Company.  These  plants  are  located  on  either  side  of 
an  indented  forebay  about  a  mile  and  a  quarter  above  the  Falls.  The  turbines  in 
station  No.  i  are  of  the  5ooo-HP.,  vertical  type,  located  at  the  bottom  of  a  pit,  and 
operate  under  a  head  of  about  135  feet.  There  are  ten  units  installed.  Power  house 
No.  2  is  designed  on  the  same  principle  and  contains  ten  55OO-HP.  units.  The  tailrace 
of  both  plants  empties  into  a  tunnel  1000  feet  long  and  discharges  into  the  gorge  at  the 
side  of  the  pillar  of  the  steel  arch  bridge.  It  might  be  of  interest  to  state,  that  after 
thirteen  years  of  continuous  operation,  the  lining,  of  ordinary  brick,  has  been  in  no 
way  damaged.  Beneath  the  Falls  at  the  water's  edge  on  the  American  side,  are 
power  houses  Nos.  2  and  3  of  the  Niagara  Falls  Power  and  Manufacturing  Company. 

On  the  Canadian  side,  the  intake  of  the  Ontario  Power  Company  plant  will  be 

1  Neuere  Turbinenanlagen.       Zeitschrift  des  Vereines  deutscher  Ingenieure,  1901,  p.  1239. 

2  Prof.  W.  C.'Unwin  made  a  rough  estimate  of  7,000,000  HP. 

327 


328 


HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 


=5   I 

«      Q. 


o  o      .j- 


TYPICAL  HYDROELECTRIC  PLANTS. 


329 


observed  to  be  the  farthest  above  the  Horse-Shoe  Falls.  Below  this  is  the  plant  of  the 
Electric  Development  Company.  It  is  equipped  with  vertical  turbines  similar  to 
those  of  the  Niagara  Falls  Power  Company.  The  tailrace  discharges  into  the  Gorge 
at  the  base  and  behind  the  Horse-Shoe  Fall.  Below  this  power  plant  is  that  of  the 
Canadian-Niagara  Power  Company,  which  is  allied  with  the  Niagara  Falls  Power 


FIG.  2. — Map  of  Niagara  Falls,  showing  Location  of  Power  Developments. 

Company.  It  is  designed  for  vertical  turbines  with  the  general  arrangement  as  the 
three  above  mentioned.  The  water  from  this  plant  is  discharged  into  the  Gorge  at 
the  foot  of  Table  Rock  Cliff.  The  four  plants  above  the  Falls  are  identical  in  many 
respects. 

Ontario  Power  Plant.1  The  largest  and  most  prominent  power  plant  contem- 
plated is  that  of  the  Ontario  Power  Company,  located  on  the  Canadian  side  of  the 
Falls.  There  is  no  installation  in  the  world  which  exceeds  it  in  capacity.  The 
power  house  is  located  in  the  Gorge  near  the  Table  Rock  Cliff,  and  draws  its  water 
above  the  Falls  among  the  Dufferin  Islands.  The  ultimate  capacity  of  the  plant 
will  exceed  200,000  HP.  This  power  is  controlled  and  distributed,  at  60,000  volts, 
from  an  isolated  distributing  station,  situated  on  the  cliff  some  600  feet  away  and 
260  feet  above  the  generating  station. 

Forebay.  The  forebay  or  intake  is  about  600  feet  long,  stretched  across  the 
inlet  of  Dufferin  Islands  and  practically  parallel  to  the  main  stream.  The  deflecting 


1  Abstract  from  a  paper  by  P.  N.  Nunn,  The  Development  of  the  Ontario   Power  Company. 
Inst.  E.  £.,  Ashville,  N.  C.,  June  19-23,  1905. 


Am. 


330 


HYDROELECTRIC   DEVELOPMENTS  AND   ENGINEERING. 


curtain  wall  of  the  outer  forebay  is  made  of  reinforced  concrete  faced  with  wooden 
planking  (see  Fig.  3).  The  water  here  is  15  feet  deep;  as  the  curtain  wall  extends 
9  feet  into  the  water,  only  deep  water  is  admitted  to  the  forebay,  and  all  floating 
material  is  deflected.  The  water,  after  entering  the  outer  forebay,  passes  through  a 
rack  into  the  inner  forebay. 

The  rack  structure  is  320  feet  long  and  lies  across  the  entrance  of  the  inner  fore- 
bay,  practically  parallel  with  the  flow  in  the  outer  forebay.  All  finer  floating  material 
which  passes  the  outer  deflecting  wall  is  deflected  by  the  main  screen  house  and 
carried  over  the  spillway  (see  Fig.  4).  At  the  foot  of  the  rack  is  a  trench  or  sand- 


FIG.  3. — Section  through  Intake  of  Forebay, 
Ontario  Power  Company. 


FIG.  4. — Section  through  Screen  House,  Ontario 
Power  Company. 


trap  to  carry  off  sand,  gravel,  etc.  The  water  at  the  screen  house  is  20  feet  deep, 
while  at  the  gate  house  it  is  30  feet  deep.  The  gate  house  is  provided  to  accommodate 
three  penstocks,  with  motor-operated  head  gates.  In  front  of  the  head  gates  are 
wide  mesh  screens  and  a  curtain  wall,  extending  about  3  feet  into  the  water,  to  prevent 
foreign  material  from  entering  the  penstock.  The  screen  and  gate  houses  are  well 
provided  with  steam  for  heating  and  thawing,  also  electrically  operated  cranes  to 
facilitate  the  changing  of  screens.  As  the  buildings  are  located  in  the  reservation, 
special  attention  has  been  paid  to  the  architectural  features  of  same. 

Penstocks.  The  main  penstocks  are  three,  of  which  two  are  installed;  are  18  feet 
in  diameter  and  laid  in  the  top  of  the  lower  cliff.  This  penstock  is  made  of  o.5-inch 
material,  reinforced  on  the  upper  half  with  bulb  tees  and  covered  with  concrete 
(see  Fig.  6).  It  is  650x3  feet  long  and  calculated  for  a  velocity  of  15  feet  per  second. 


TYPICAL  HYDROELECTRIC  PLANTS. 


331 


FIG.  5. — Section  through  Gate  House,  Ontario  Power  Company. 


FIG.  6. — i8-foot  Penstock,  partly  embedded  in  Concrete,  Ontario  Power  Company. 


332  HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 

At  the  end  of  the  penstock  above  the  power  house,  cut  in  the  rock,  is  the  valve 
chamber,  from  whence  seven  branches,  9  feet  in  diameter,  lead  down  to  the  turbine 
room,  supplying  water  at  a  velocity  of  10  feet  per  second.  The  main  penstock  also 
has  two  3o-inch  branches  for  supplying  the  exciter  turbines.  These  branches  are 
provided  with  electrically  operated  gate  valves  controlled  from  the  generating  room, 
and  run  vertically,  then  horizontally,  to  the  turbines.  At  the  bend  they  are  securely 
anchored,  being  embedded  in  concrete.  Each  branch  is  provided  with  two  expansion 
joints.  At  the  end  of  the  main  penstock  is  a  spillway,  with  a  helical  discharge. 
The  function  of  the  spillway  is  to  act  as  a  relief  valve,  in  case  a  generator  dropped 
its  load.  The  characteristic  features  of  the  spillway  are,  the  adjustable  weir  and 
helical  discharge,  which  preserves  a  smooth,  unbroken  water  column,  with  highest 
velocity  and  least  expenditure  of  energy.  This  scheme  has  been  adopted  to  pre- 
vent erosion,  restricted  flow  and  excessive  air  suction,  the  latter  on  account  of  the 
formation  of  ice  from  spray  under  forced  circulation  of  air. 

Power  House.  The  power  house  is  located  at  the  bottom  of  the  cliff,  and  is  76 
feet  wide  with  an  ultimate  length  of  1000  feet.  The  main  turbines  are  arranged  in 
a  single  row,  and  the  exciter  turbines  are  set  in  recesses  (see  plan  and  cross  section). 
The  cross  section  is  taken  through  the  extreme  width,  including  the  recesses. 

The  whole  building,  including  the  roof,  is  made  of  concrete  and  reinforced 
concrete.  It  is  of  handsome  design,  both  exterior  and  interior.  The  walls  of  the 
latter  are  faced  with  white  enameled  brick.  The  turbine  room  is  served  by  a  5<D-ton, 
electrically  operated  crane. 

Turbines.  The  power  plant  is  designed  to  accommodate  twenty-two  turbines;  at 
present  there  are  six  installed.  They  are  of  the  horizontal  Francis  type;  two  turbines 
are  opposed  and  mounted  on  the  same  shaft.  Each  has  its  own  feeder  penstock  and 
discharges  into  a  common  draft  tube,  10  feet  in  diameter.  The  runner  is  of  cast 
steel  and  78  inches  in  diameter.  The  housing  is  of  structural  steel,  rectangular  in 
plan  and  spiral  in  elevation,  and  16  feet  in  diameter.  These  turbines  operate  under 
a  head  of  175  feet,  20  feet  of  which  is  secured  in  the  draft  tube,  and  develop  at  a  speed 
of  187.5  R-P-M.,  12,000  HP.  They  were  designed  and  built  by  J.  M.  Voith,  Heiden- 
heim,  Germany.  The  speed  of  each  turbine  is  controlled  by  a  Lombard  governor, 
located  on  the  mezzanine  floor,  and  are  motor  controlled,  for  synchronizing,  from  the 
control  room.  At  the  end  of  the  penstock  branches  to  the  turbines,  provision  is 
made  for  drainage;  also  hydraulically  operated  relief  valves  are  installed. 

Generators.  The  generators,  of  Westinghouse  make,  are  rigidly  coupled  to  the 
driving  shaft.  They  are  of  the  three-phase  type,  25-cycle,  12,000- volt,  capable  to 
develop  at  normal  speed,  8000  K.W.  The  total  weight  of  a  generator  is  231  tons. 

Exciters.  The  exciters  are  located  on  the  mezzanine  floor;  two  are  at  present 
installed.  Each  has  a  capacity  of  500  HP.,  furnishing  current  at  250  volts.  Each 
is  coupled  to  its  own  turbine  of  the  Francis  type,  fed  by  30-inch  penstocks. 

Generator  Auxiliaries.  There  is  a  separate  distributing  station,  in  which  is  located 
the  bulk  of  the  switching  gear.  At  the  operating  gallery  in  the  power  house  is  located 
in  groups  of  six,  12,000- volt  oil  switches  controlling  the  output  of  each  generator. 
Here  are  also  located  the  field  rheostats,  of  which  there  are  at  present  six  installed. 


TYPICAL  HYDROELECTRIC  PLANTS. 


333 

UNfV.  < 


il     '      1 


FIG.  7. — Relative  Location  of  Penstocks,  Power  Plant  and  Distributing  Station,  Ontario  Power 

Company. 


i\    I  :    !        li    i 


FIG.  8. — Plan  of  Power  Plant  and  Distributing  Station,  Ontario  Power  Company. 


334  HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 


TYPICAL  HYDROELECTRIC   PLANTS. 


335 


I 

o 

'i 


<u 

I 


o 

IH 

- 


336 


HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 


In  front  of  the  oil  switches  on  the  operating  gallery  is  located  a  switchboard,  having 
a  panel  for  each  generator,  upon  which  are  mounted  an  electrically  operated  field 
circuit  breaker,  an  ammeter  and  control  switch  for  tripping  the  first  generator  oil 
switch.  This  switchboard  also  contains  two  panels,  one  for  each  exciter,  upon  which 
are  mounted  the  customary  switches,  a  voltmeter  and  ammeter.  Alongside  of  the 
exciter  board  is  a  panelboard,  having  the  necessary  switches  for  controlling  the 
distribution  of  alternating  and  direct  current,  for  lighting  and  power  service  in 
the  power  house,  also  for  controlling  the  penstock  valves  in  the  valve  chamber. 

Back  of  the  exciter  board  are  panels,  one  for  two  generators,  upon  which  are 
mounted  the  terminals  of  the  control  wires  and  relays  for  the  automatic  operation 
of  the  generators.  Under  ordinary  conditions,  the  operator  has  to  attend  to  the 
exciter  current  only;  and  only  in  case  of  emergency,  does  he  attend  to  the  generator 
and  field  switches. 


FIG.  ii. — Interior  of  Ontario  Power  Plant. 


Generator  Leads.  The  leads  from  the  generators  are  single  conductors;  they  are 
insulated  with  threaded  cambric,  mounted  upon  insulators,  each  in  a  separate 
compartment,  made  up  of  thin  reinforced  concrete  shelves.  Field  circuits,  exciter 
leads  and  control  wires  are  carried  in  iron  conduits.  From  the  oil  switches  in  the 
generating  room  to  bell-manholes  in  the  distributing  station,  the  generator  leads 
are  of  the  three-conductor  type  and  in  duplicate.  They  are  led  through  a  tunnel 


TYPICAL  HYDROELECTRIC  PLANTS. 


337 


9  feet  square  and  having  an  incline  of  30  degrees,  in  which  are  also  located  the  exciter 
turbine  penstocks.  After  passing  under  the  main  penstock,  the  generator  leads  are 
run  to  a  manhole  located  midway  between  the  power  house  and  the  distributing 


FIG.  12. — Section  through  Distributing  Station,  Ontario  Power  Company. 


FIG.  13. — Control  Room,  Ontario  Power  Company. 

station.  From  this  manhole  the  cables  run  through  tile  ducts.  The  cables  are 
paper  insulated,  lead  covered,  over  which  is  a  spirally  wound  ribbon  covered  with 
jute.  Special  precaution  has  been  taken  to  see  that  all  cables  are  well  isolated  and 
so  located  that  they  may  be  easily  inspected. 


338 


HYDROELECTRIC   DEVELOPMENTS   AND   ENGINEERING. 


Distributing  Station.1  The  distributing  station  is  situated  on  a  hill  above  the  cliff 
and  is  about  260  feet  above  the  generating  station.  It  is  about  500  feet  long  and 
125  feet  wide,  with  a  central  wing  for  offices, etc.,  and  designed  to  accommodate  twenty 
transformer  groups.  The  present  installation  is  built  to  accommodate  six  groups. 


FIG.  14. — Transformer  Compartment,  Ontario  Power  Company. 

As  will  be  seen  in  the  accompanying  illustration,  the  distributing  station  is  divided 
into  high  and  low  tension  bays,  between  which  is  located  the  transformer  room 
separated  by  partition  walls.  In  the  middle  of  the  transformer  room  and  isolated 
by  partition  walls,  is  located  the  control  room.  Unlike  the  power  house,  which  has 

1  Abstract  from  a  paper  by  V.  G.  Converse,  The  Electrical  Plant  of  the  Ontario  Power  Company, 
Canadian  Electrical  Association,  Niagara  Falls,  June  19-21,  1906. 


TYPICAL  HYDROELECTRIC  PLANTS.  339 

been  begun  at  one  end,  the  distributing  station  has  been  begun  in  the  middle,  because 
it  was  thought  to  be  more  economical  in  space,  and  also  due  to  the  symmetrical 
arrangement  of  the  station. 

Wiring  System.  The  accompanying  diagram  clearly  illustrates  the  general  layout 
of  the  wiring  system.  It  will  be  seen  that  the  generators  may  feed  either  of  the  two 
bus-bar  systems,  or  may  go  directly  to  the  transformers.  Low-tension  outgoing 
feeders  may  be  thrown  on  either  of  the  busses.  Sufficient  oil  switches  are  provided 
to  give  the  most  flexible  system  of  switching.  On  both  sides  of  each  oil  switch  are 
disconnecting  switches,  to  facilitate  inspection.  All  switches  feeding  busses,  both 
high  and  low  tension,  are  equipped  with  overload  and  reverse  current  relays,  while 
switches  drawing  current  from  the  busses  have  overload  and  time  limit  relays.  The 
switches  in  the  generating  room  can  be  opened  and  closed  from  the  control 
room. 

Low-Tension  Room.  The  generator  leads  entering  the  low-voltage  bus-bar  room 
are  single-conductor  cables,  placed  in  compartments  made  up  of  reinforced  concrete. 
The  low-tension  switches  are  arranged  in  two  parallel  rows  and  separated  in  groups, 
each  comprising  a  unit.  They  are  of  the  Westinghouse  solenoid  plunger  type. 

Transformer  Room.  The  transformers  are  located  three  in  a  compartment.  They 
are  of  the  Westinghouse  water-cooled  oil  type.  Each  has  a  capacity  of  3000  K.V.A. 
and  weighs,  when  filled  with  oil,  approximately  50  tons.  They  are  wound  in  delta 
on  the  low-tension  and  star  on  the  high-tension  side  with  center  grounded.  The 
secondary  potential  of  each  transformer  is  36,000  volts,  and  as  connected,  the  resultant 
line  voltage  is  approximately  62,000  volts.  On  the  low-tension  side  of  the  transformer 
compartments  is  a  track  space,  providing  facilities  for  assembling  and  repairs.  On 
the  high-tension  side  of  the  transformer  pit,  separated  by  a  low  wall,  are  located 
choke  coils.  The  transformer  room  is  served  by  an  electrically  operated  crane  for 
handling  transformers  and  choke  coils.  The  oil  and  water  piping  is  located  between 
the  foundations  of  the  transformers.  As  will  be  seen  in  Fig.  15,  the  cables  which 
are  insulated  with  cambric  and  covered  with  a  coating  of  asbestos,  leave  the  trans- 
former room  through  insulating  bushings,  set  in  circular  panels  in  the  division  walls 
between  the  transformer  room  and  high-tension  room. 

High-Tension  Room.  In  the  high-tension  room,  the  series  transformers  and  oil 
switches  are  located  on  the  floor,  while  the  busses,  made  up  of  copper  pipes  wrapped 
with  threaded  cambric  and'asbestos  braid,  are  mounted  six  feet  apart  on  the  top  of  high 
walls  which  separate  the  units  and  are  well  provided  with  disconnecting  switches. 
The  high-tension  switches  are  built  on  the  same  plan  as  the  low-tension,  but  are  larger, 
because  of  their  longer  break  and  greater  insulating  distance.  The  oil  tanks  are  of 
steel  and  have  a  capacity  of  500  gallons  each.  Oil  pipes  and  control  wires  for  actuat- 
ing the  switches  are  carried  beneath  the  floor.  In  every  other  compartment  are  series 
transformers  and  oil  switches  for  feeder  circuits.  The  outgoing  feeders  pass  through 
insulating  bushings  carried  in  double  glass  panels  set  in  the  wall  near  the  ceiling.  On 
the  outside  of  the  wall  they  are  protected  by  an  overhanging  hood.  A  portion  of  the 
high-tension  room  is  reserved  for  outgoing  low-tension  (12,000- volt)  feeders,  their 
auxiliaries,  and  also  for  the  service  busses. 


340 


HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 


Control  Room.  On  the  top  floor  of  the  middle  section  of  the  distributing  station 
is  the  control  room;  directly  underneath  on  a  mezzanine  floor  are  the  recording  instru- 
ment boards,  and  on  the  floor  beneath  are  terminal  boards.  On  the  floor  of  the  control 
room  are  located  in  a  semicircle  the  control  pedestals,  and  directly  behind  them  are 
placed  the  instrument  columns.  The  semicircle  is  broken  in  the  middle  to  permit 
the  placing  of  the  feeder  control  panel.  In  the  center  of  the  room,  overlooking  all  the 
instruments,  is  located  the  desk  of  the  chief  operator,  from  which  he  can  direct  his 
assistants.  The  control  pedestals,  one  for  each  generator,  contain  the  following 
instruments:  switches  for  the  control  of  the  oil  circuit  switches,  push  buttons  for  open- 
ing and  closing  generator  field  switch,  controller  for  the  field  rheostat,  and  controller 


FIG.  15. — High  Tension  Bus  Bars  and  Outgoing  Feeders,  Ontario  Power  Company. 

for  operating  the  motor  on  the  turbine  governer  for  synchronizing.  Each  pedestal 
has  dummy  bus  bars  and  signal  lamps.  Upon  each  instrument  column  are  mounted 
a  voltmeter,  wattmeter,  ammeter,  power  factor  indicator,  frequency  meter,  a  synchro- 
scope and  three  ammeters  connected  to  the  leads  of  the  transformers.  Upon  each 
feeder  control  panel  are  mounted  the  switches  and  pilot  lamps  for  the  control  of  oil 
circuit  breakers  in  the  duplicate  feeders,  and  three  ammeters  for  feeder  circuits.  On 
either  side  of  the  entrance  to  the  control  room,  opposite  the  semicircle  are  two  service 
boards,  one  of  which  contains  the  switches  and  instruments  required  for  the  dis- 
tribution of  220-volt  alternating  current  for  light  and  power  purposes  in  the  building. 
This  board  also  contains  the  switches  for  operating  the  oil  switches,  located  in  the 


TYPICAL  HYDROELECTRIC   PLANTS. 


341 


1 2,000- volt  service  bus.  Upon  the  other  board  are  mounted  the  switches  and  instru- 
ments for  the  2 50- volt  direct  current  distribution  for  lighting  and  control  purposes. 
The  direct  current  is  at- present  obtained  from  the  exciters.  On  this  board  is  also  a 
panel  controlling  a  storage  battery,  which  acts  as  an  emergency  direct  current  supply. 
This  storage  battery,  of  a/p-ampere-hour  capacity,  is  located  in  the  basement,  where 
are  also  located  the  assembly  racks  for  control  and  instrument  wires. 

Transmission  Line.1    In  the  charter  granted  to  the  Ontario  Power  Company,  as 
well  as  the  other  Canadian  Niagara  Falls  power  plants,  all  power  generated  must  be 


FIG.    16. — 62,ooo-volt   Transmission    Line   near   the    Distributing   Station.     Three-Legged 
Steel-Tube  Towers,  Ontario  Power  Company. 

transmitted  outside  of  Victoria  Park,  and  that  on  demand,  one-half  of  the  power  gen- 
erated must  be  supplied  to  Canadian  consumers  at  the  same  rate  as  the  consumers  on 
the  American  side.  There  is  no  export  or  import  duty  demanded  by  either  govern- 
ment on  the  transmission  of  power.  As  industry  on  the  Canadian  side  is  not  developed 
to  a  great  extent,  the  bulk  of  the  power  is  transmitted  to  the  American  side,  over  160 
miles  of  transmission  lines.  As  the  American  lines  embody  many  typical  features,  the 
following  is  submitted. 

1  The  Transmission  Plant  of  the  Niagara,  Lockport  and  Ontario  Power  Company,  by  R.  D.  Mershon. 
Am.  Inst.  E.  £.,  September,  1907. 


342  HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 


FIG.  17. — Niagara  Crossing,  General  View. 


TYPICAL  HYDROELECTRIC  PLANTS. 


343 


FIG.  18. — Niagara  Crossing  Cantilever,  American  Side. 


FIG.  19. — Cross  Connecting  and  Disconnecting  Switches  and  Open  Air  Fuses  at  Point  of 
Junction  of  Auburn  Branch  Line  and  the  Main  Line.  Niagara,  Lockport  and  Ontario 
Power  Company's  Line. 


344 


HYDROELECTRIC  DEVELOPMENTS  AND  ENGINEERING. 


From  the  distributing  station  a  line  of  steel  towers  extends  northward,  a  distance 
back  from  the  river  to  a  point  four  miles  down  the  gorge,  where  the  lines  cross  the 
latter.  Here  the  lines  drop  to  cantilever  arms  projecting  over  the  edge  of  the  bank, 
thence  to  steel  towers  erected  on  the  Canadian  shore  of  the  river.  From  here,  they 
cross  the  gorge  with  a  span  of  600  feet  to  the  American  side,  where  similar  towers  are 


FIG.  20. — Four-Legged  Tower  on  "Floating"  Foundation,  Montezuma  Swamp.    Niagara, 
Lockport  and  Ontario  Power  Company's  Line. 


erected,  thence  to  the  cantilevers  and  the  switch  house  on  the  American  side.  Dupli- 
cate lines  lead  to  Lockport,  16  miles  east,  each  capable  of  transmitting  30,000  HP. 
From  Lockport  to  Mortimer,  57  miles,  each  line  is  designed  to  transmit  20,000  HP. 
From  Mortimer  to  Syracuse,  81  miles,  each  line  is  capable  of  transmitting  10,000  HP. 
From  Lockport  to  a  point  n  miles  east,  thence  south,  to  the  West  Shore  Railroad, 


TYPICAL  HYDROELECTRIC  PLANTS.  345 

thence  to  Pittsford,  is  a  line  of  20,000  HP.  From  Pittsford,  along  the  West  Shore  Rail- 
road, to  Syracuse,  is  a  line  of  10,000  HP.  From  Lockport  to  a  point  south  of  Buffalo 
are  two  transmission  lines,  each  having  a  capacity  of  30,000  HP.  The  major  part  of 
the  lines  run  on  private  right  of  way,  varying  from  75  to  300  feet  in  width.  The  trans- 
mission towers,  with  the  exception  of  that  portion  of  the  main  line  on  the  West  Shore 
Railroad,  between  Ohurchville  and  Syracuse,  composed  of  wooden  A-frame  structures, 
are  of  structural  steel,  spaced  500  feet  apart  as  standard.  In  some  portions  of  the  line 
the  spans  are  longer,  the  longest  being  1253  feet,  which,  of  course,  requires  higher  and 
special  designed  towers.  The  first  towers  installed  are  of  the  three-legged  type,  made 
up  of  steel  tubes,  while  the  bulk  are  of  structural  steel,  heavily  galvanized.  Of  this 
latter  there  are  two  types,  the  guyed  and  unguyed;  the  former  are  provided  with  guys 
and  double  sets  of  insulators.  The  guyed  towers  are  placed  at  intervals,  anchored 
in  both  directions  of  the  line.  Their  duty  is  to  meet  the  contingency  of  all  three  cables 
breaking  on  one  side  of  the  tower.  The  towers  are  set  in  reinforced  concrete  founda- 
tions with  a  broad  base  to  utilize  the  weight  of  the  earth  around  them  in  resisting  uplift. 
The  towers  and  their  foundations  are  capable  of  withstanding  the  transverse  force 
which  will  be  brought  upon  them  when  covered  with  15  inches  of  ice  all  around  and 
the  wind  blowing  transversely  to  the  line  at  75  miles  per  hour.  The  towers  are  shipped 
knocked  down  and  assembled  in  the  field.  They  are  erected  by  means  of  a  field 
derrick  and  a  team  of  horses.  The  insulators  on  the  main  line  are  14.5  inches  diam- 
eter, three-petticoat  type.  The  three  parts  are  cemented  together  and  the  whole 
mounted  on  a  cast  steel  pin,  bolted  by  three  bolts  to  the  structure  of  the  tower.  The 
total  height  of  these  insulators  is  19  inches.  The  insulators  on  the  branch  lines  are  of 
less  expensive  design.  Each  branch  has,  where  it  is  tapped  on  the  main  line,  60,000 
volt  outdoor  fuses,  consisting  of  thin  copper  wire  16  feet  long,  incased  in  a  rubber  tube, 
mounted  on  wooden  bars,  supported  by  line  insulators  and  mounted  on  a  pole.  Three 
sizes  of  cable  are  employed  and  designated  as  3/3,  2/3,  1/3.  The  3/3  cable  is  of 
aluminum,  and  consists  of  19  strands,  having  a  total  area  of  642,800  circular  mils, 
being  equivalent  to  400,000  circular  mils  of  copper.  The  cross-section  area  of  the 
others  is  2/3  and  1/3  respectively  of  the  3/3.  The  cables  are  held  in  place  on  the 
insulators  by  aluminum  tie  wires.  All  joints  are  of  the  twisted  sleeve  type.  At  inter- 
vals along  the  line  are  placed  disconnecting  switches  to  cut  out  sections  when  neces- 
sary. Some  of  the  disconnecting  switches  are  arranged  as  cross-connecting  switches. 
At  intervals  along  the  line  are  located  patrol  houses,  for  storage  purposes  and  accommo- 
dating patrolmen.  The  accommodations  consist  of  kitchen,  sleeping  and  sitting  room. 
A  private  telephone  line  runs  the  entire  length  of  the  system  on  wooden  poles.  Station- 
ary and  portable  telephones  are  provided. 

Substations.1  There  are  at  present  installed  along  the  line  three  substations, 
at  Lockport,  Gardenville  and  Baldwinsville,  respectively.  The  two  former  have  each 
at  present  a  normal  capacity  of  3000  K.W.  and  are  designed  for  additional  increase. 
The  latter  has  a  capacity  of  750  K.W.  The  bus  bar  system  of  the  substation  is  out 
of  doors,  i.e.,  the  bus  bars  have  been  treated  as  though  they  were  a  part  of  the  trans- 
mission line,  and  are  located  outdoors.  In  connection  with  same  are  disconnecting 

1  See  Electrical  World,  May  a,  1908. 


346 


HYDROELECTRIC   DEVELOPMENTS   AND   ENGINEERING. 


switches  for  making  various  connections  of  apparatus.  Disconnecting  switches  are 
not  intended  to  break  the  working  current.  When  it  is  necessary  to  break  the  circuit 
under  load,  it  will  be  done  by  high  tension  oil  switches,  connected  in  the  substations 


FIG.  21. — Lockport  Substation,  showing  Outdoor  6o,ooo-volt  Bus  Bars. 

In  a  similar  way  are  located  the  horn  type  lightning  arresters.  Each  phase  is 
provided  with  three  lightning  arresters  set  with  gaps  of  different  lengths.  One  is  set 
for  low  striking  distance,  and  has  in  series  with  it  a  high  resistance;  the  next  is 
set  for  higher  striking  E.M.F.,  and  has  in  series  a  low  resistance;  the  third  pair  is 


TYPICAL  HYDROELECTRIC  PLANTS. 


347 


set  for  very  high  striking  force  and  has  a  fuse  in  series.  Slight  static  discharges  are 
relieved  by  the  lowest  set  arrester,  a  higher  discharge  by  two  lowest,  and  in  extreme 
cases,  all  three  operate. 

The  equipment  of  the  substations  is  similar  to  that  found  in  everyday  practice. 
To  provide  for  a  cooling  system  for  the  oil  transformers,  wells  had  to  be  sunk  and 
pumping  plants  installed,  also  water  towers  and  a  cooling  pond,  the  latter  to  be  used 
in  case  the  wells  failed  to  supply  water.  A  complete  oil  piping  system  for  the  trans- 
formers is  installed.  Private  transformer  substations  are  located  in  Auburn  and 


FIG.  22. — 6o,ooo-volt  Circuit  Breaker,  Lockport  Substation. 


Syracuse.  The  station  at  Auburn  supersedes  and  supplements  the  steam  generating 
apparatus  of  the  Auburn  Light,  Heat  and  Power  Company.  This  company  pur- 
chases power  according  to  a  system  of  charges  based  on  one-minute  peak  loads,  so 
that  it  is  advantageous  to  maintain  a  high  load  factor.  For  this  purpose,  a  certain 
portion  of  the  steam-driven  apparatus  has  been  retained. 

In  connection  with  the  Syracuse  end  of  the  line,  the  Syracuse  Rapid  Transit 
Company  has  a  two-mile  60,000- volt  transmission  line,  leading  from  the  city's  western 
boundary  to  the  substation  at  Tracy  Street,  on  the  bank  of  the  Erie  Canal.  There 
are  forty  specially  designed  structural  steel  towers,  varying  in  height,  from  45  to  63 
feet.  Each  leg  of  the  three-phase  circuit  consists  of  a  seven-strand  seven-sixteenths 
plow  steel  cable.  The  average  span  is  240  feet,  the  longest  497  feet. 


348  HYDROELECTRIC   DEVELOPMENTS   AND  ENGINEERING. 

THE    GREAT    FALLS    POWER    PLANT    OF    THE    SOUTHERN    POWER    COMPANY, 

CHARLOTTE,    N.  C. 

The  Southern  Power  Company  owns  and  controls,  in  all,  nine  water-power  sites 
in  the  so-called  Piedmont  section,  embracing  the  Sand  Hill  district,  extending  from 
the  foot  of  the  Blue  Ridge  Mountains,  a  distance  averaging  probably  120  miles. 
One  water  power  with  a  capacity  of  12,000  HP.,  lies  on  the  Broad  River  of  the 
Carolinas,  equidistant  from  Gaffney  and  Blacksburg,  S.  C.,  while  the  other  is  located 
on  the  Wateree  River,  of  which  the  Catawba  River  is  the  principal  tributary.  This 
one  is  capable  of  developing  20,000  HP.  All  others  are  on  the  Catawba  River. 
The  aggregate  of  these  powers  amounts  to  145,000  HP.,  which  will  be  transmitted 
over  an  area  150  miles  long  and  about  100  miles  wide.  Of  these  different  water 
power  sites,  the  one  known  as  the  Great  Falls  of  the  Catawba  was  the  best  for  initial 
development. 

Great  Falls  consists  of  a  series  of  falls  and  shoals,  having  a  total  head  of  176  feet 
in  a  distance  of  eight  miles,  the  development  of  which  will  require  three  separate 
plants. 

The  lowest  of  these  necessitates  the  construction  of  a  dam  across  the  river,  at  a 
point  just  below  the  mouth  of  Rocky  Creek,  having  a  drainage  area  of  4450  square 
miles;  a  development  of  60  feet  head  is  here  visible.  With  the  construction  of  a 
dam  immediately  above  the  mouth  of  Fishing  Creek,  40  feet  can  be  developed;  the 
drainage  area  will  be  3900  square  miles. 

The  middle  development,  with  a  head  of  72  feet,  has  a  drainage  area  of  4200  square 
miles,  and  is  known  as  the  Great  Falls  station,  the  subject  of  this  description.1 

The  essential  features  of  this  development  consist  of  a  low  spillway  dam  at  the 
head  of  Mountain  Island,  diverting  the  water  into  the  western  channel;  near  the  foot 
of  the  island  are  the  head  gates  and  another  spillway  dam,  as  seen  in  Fig.  i;  an 
extension  of  this  dam  serves  as  an  overflow  weir  between  the  canal  and  the  river. 
From  this  point  the  stream  is  carried  through  a  valley  1.25  miles  to  the  power  house, 
where  a  retaining  bulkhead  is  built  across  the  valley;  the  tailrace  discharges  into 
Rocky  Creek. 

Spillway.  The  main  spillway  at  the  head  works  is  438.8  feet  long  at  the  crest 
line,  with  an  average  head  of  30  feet;  it  has  a  batter  of  i  :  10  on  the  upstream  face. 
The  width  at  the  base  is  41  feet. 

The  spillway  dam  in  the  canal  is  of  similar  design,  521.2  feet  long  on  the  crest, 
and  37.75  feet  wide  at  the  bottom;  the  average  height  is  36  feet.  The  crest  on  this 
weir  is  one  foot  higher  than  the  main  spillway.  It  is  built  up  of  cyclopean  masonry, 
the  concrete  being  1:2:5;  tne  biggest  stones  are  as  large  as  could  be  handled  by 
the  derricks.  Sectional  forms  were  used  to  the  greatest  practical  height,  the  upper 
curves  being  then  finished  by  hand  and  template. 

The  inlet  to  the  headrace  is  provided  with  ten  sets  of  coarse  racks  consisting  of 
5  by  three-eighths  inch  bars  on  3-inch  centers,  each  being  16  feet  wide,  and  18.5  feet 

1  The  Great  Falls  Station  of  the  Southern  Power  Co.,  by  Curtis  A.  Mees  and  John  H.  Roddey.  The 
Engineering  Record,  May  18,  25,  and  June  i,  1907. 


TYPICAL  HYDROELECTRIC  PLANTS. 


349 


350 


HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 


I 


Q. 

s 

o 
U 


I 

0, 

o 


TYPICAL  HYDROELECTRIC  PLANTS. 


351 


352 


HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 


high,  held  by  piers  45  feet  high,  5  feet  across  and  8  feet  wide  at  the  top,  with  a  3  :  i 
batter  downstream,  forming  a  buttress.  Piers  are  also  carried  out  on  the  upstream 
side  for  the  support  of  the  structure.  These  have  a  batter  of  12  15,  giving  the  section 
at  the  base  a  total  width  of  47  feet. 

The  gate  frames  are  of  structural  steel  and  of  the  same  design  as  those  at  the 
penstock  inlet,  and  are  provided  with  by-passes  for  the  purpose  of  relieving  them  of 
pressure  before  raising.  There  is  a  4  by  5-foot  Coffin  sluice  gate  for  drainage 
purposes. 

Main  Dam.  The  bulkhead,  or  main  dam,  to  which  the  power  house  is  adjoined, 
has  a  width  at  the  top  of  8  feet;  the  upstream  face  is  vertical,  the  downstream  face 
is  battered  1.75  :  i.  The  height  in  the  center  of  the  valley  is  about  90  feet.  The 
cross  section  is  largely  increased  in  that  section  opposite  the  power  house,  for  here 
are  built,  through  the  bulkhead,  the  intake  flumes  to  the  turbines,  which  are  also 
located  in  this  section;  whereas  the  generator  is  located  in  the  power  house  built 
immediately  below  the  bulkhead,  virtually  forming  a  part  of  it. 

At  either  end  of  the  power  house  in  this  wall  there  are  two  48-inch  Coffin  sluice 
gates  for  by-passing  leaves  and  small  debris  from  the  racks. 

The  water,  before  it  enters  the  turbine  intakes,  has  to  pass  through  screens  of 
4  by  one-fourth-inch  grid  bars  spaced  1.5  inches  on  centers,  and  structural  steel 
gates,  each  of  which  is  provided  with  two  by-pass  or  filling  gates,  9  by  14  inches. 

Eight  of  these  gates  admitting  water  to  the  main  turbines  are  built  of  6-inch 
I-beams  covered  with  three-eighth-inch  steel  plate  on  the  outer  side.  On  the  inner 
side  they  have  bronze  running  strips  on  the  guides,  while  machined  bearing  plates 
at  top  and  bottom  insure  tightness  when  the  gates  are  closed. 

There  are  two  smaller  gates  constructed  of  4-inch  I-beams,  admitting  water  to 
the  exciter  turbines;  each  is  provided  with  a  filling  gate  9  by  12  inches.  The  exciter 
gates  are  operated  by  hand,  while  the  main  gates  are  operated  by  means  of  a  motor 
located  in  a  small  house  on  the  top  of  the  bulkhead.  The  motor  receives  250  volts 
from  the  exciter  units. 

Turbines.  There  are  eight  main  turbo-units  5200  HP.  making  225  R.P.M.  under 
a  head  of  72  feet,  and  two  700  HP.  exciter  turbines  making  450  R.P.M.  Each  unit 
consists  of  a  pair  of  horizontal  twin  turbines  with  top  inlet  and  central  discharge. 
Two  of  the  main  units  were  furnished  by  the  Holyoke  Machine  Company,  the 
remainder  by  the  Allis-Chalmers  Company. 

The  former  have  a  guaranteed  efficiency  as  follows: 


Discharge  

Full 

1 

| 

| 

l 

Efficiency  per  cent  

81 

82 

81 

74 

68 

The  efficiencies  of  the  latter  make  are: 


Discharge  

Full 

I 

J 

J 

} 

{ 

Efficiency,  per  cent  

80 

81 

82 

80 

78 

60 

TYPICAL  HYDROELECTRIC  PLANTS. 


353 


354 


HYDROELECTRIC  DEVELOPMENTS  AND  ENGINEERING. 


I- 


I 

*-> 

I 


I 
I 

c 

6 


10 

6 


TYPICAL  HYDROELECTRIC  PLANTS. 


355 


The  runners  of  the  Holyoke  turbines  are  48  inches  in  diameter.  The  runners 
of  the  Allis-Chalmers  turbines  are  53  inches  in  diameter,  and  the  draft  connection 
ii  feet  in  diameter,  which  gradually  increases  to  18  feet  3  inches,  by  n  feet  2  inches. 
The  intake  flumes  are  18.5  feet  by  16  feet,  and  taper  down  to  15  feet  in  diameter  at 
the  turbine  casing. 

The  runners  of  the  exciter  turbines  are  24.5  inches  in  diameter.  The  intake  of 
the  same  is  9  feet  high  with  semicircular  ends  of  3-foot  radius,  tapering  down  to 
6  feet  in  diameter  at  the  turbine  casing.  The  draft  tubes  are  5  feet  6  inches  in 
diameter  at  the  casing,  and  flare  to  a  width  of  9  feet  10  inches,  with  semicircular  ends 
of  2  feet  9  inches  radius. 

As  the  turbines  are  located  in  the  body  of  the  dam,  a  tunnel  in  the  latter  is 
provided,  so  that  access  may  be  had  to  the  outside  bearings. 

The  turbo-generator  sets  are  controlled  in  pairs  by  Lombard  governors;  there  is 
one  type  "N"  governor  for  two  sets  of  main  turbines,  while  the  two  exciter  units 
are  controlled  by  a  single  type  "P"  governor.  The  "N"  type,  developing  31,000 
foot-pounds,  are  guaranteed  to  completely  open  and  close  the  gates  in  1.5  seconds; 
while  the  "P"  type,  developing  6700  foot-pounds,  in  4  seconds.  The  former  are 
electric  controlled  from  the  switchboard. 

There  are  4  by  6-inch  triplex  pumps  operated  by  belts  from  the  turbine  shafts; 
these,  and  the  pressure  tanks  are  located  in  the  above  mentioned  tunnel. 

Power  House.  The  power  house  is  250  feet  long  and  37  feet  wide.  Adjoining 
same  is  a  two-story  switch  and  transformer  house  85  feet  long  and  75  feet  wide. 
The  generating  room  is  well  provided  with  20-inch  roof  ventilators,  and  is  served  by 
a  25-ton  hand  crane,  with  a  5-ton  auxiliary  trolley. 

On  the  main  floor,  in  the  switch  and  transformer  house,  are  located  the  low 
tension  oil-switches  and  transformers,  while  on  the  upper  floors  is  the  high  tension 
apparatus. 

Generators.  The  main  generators  are  of  3000  K.W.  capacity,  60  cycles,  2300 
volts.  The  exciters  are  400  K.W.  capacity,  250  volts.  The  guarantee  of  the  main 
generators  is  as  follows: 


Load                        

Full 

I 

} 

\ 

Efficiency   per  cent   

06 

QC.  C 

04 

oo 

The  temperature  is  guaranteed  not  to  exceed  35°  C.,  after  24  hours  run  at  normal 
load,  and  50°  C.,  at  37.5  per  cent  overload  for  the  same  duration. 
The  guaranteed  efficiencies  of  the  exciters  are  as  follows: 


i 

§ 

| 

Full 

ij 

Efficiency    per  cent        

so 

88 

01 

02 

02 

356 


HYDROELECTRIC   DEVELOPMENTS   AND  ENGINEERING. 


Switchboard.  As  will  be  noticed  in  the  accompanying  illustration,  the  switchboard 
is  located  several  feet  above  the  floor  on  a  raised  platform.  It  is  made  of  blue  Ver- 
mont marble  and  contains  two  transformer  panels,  two  double-circuit  feeder  panels, 
one  station  and  two  blank  panels. 

In  front  of  the  switchboard,  arranged  in  a  semicircle,  are  eight  instrument  posts 
and  eight  pedestals  for  controlling  the  main  generators.  Switchboard,  instrument 
columns,  and  control  pedestals  are  well  equipped  according  to  modern  practice. 


FIG.  6. — Power  House,  seen  from  Tailrace,  Southern  Power  Company. 

The  generator  leads  are  lead-covered  cables,  and  run  through  tile  ducts  laid  in  the 
floor. 

Wiring  Diagram.  There  are  two  sets  of  exciter  bus  bars  and  one  main  generator 
bus.  The  generators  feed  the  latter  through  non- automatic  oil  circuit  breakers; 
between  the  transformers  and  the  low  tension  bus  are  located  overload  time  limit 
oil  circuit  breakers.  Between  the  transformers  and  the  high  tension  bus  (44,000 
volts)  are  reverse  current  circuit  breakers.  Both  bus  bars  are  divided  up  into  two 
sections  by  sectionalizing  switches,  on  both  sides  of  which  are  disconnecting  switches. 
The  outgoing  feeders  are  provided  with  overload  time  limit  circuit  breakers. 

The  whole  wiring  diagram  is  such  that  two  generators  can  feed,  through  one 
transformer,  a  single  transmission  circuit,  or  they  may  feed  any  of  the  transformers 
or  outgoing  lines.  Again,  the  transformers  may  feed  directly  the  outgoing  feeders 
by  by-passing  the  high  tension  bus  bar. 

The  tow  tension  bus  bar  is  made  up  of  five  strips  of  3  by  one-fourth  inch  copper, 


TYPICAL  HYDROELECTRIC  PLANTS. 


.  OF 


O, 

a 

o 
U 

«-i 
<u 

o 


bfl 


o 

U-l 

O 
S-, 

O 


358 


HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING, 


clamped  together.  These  and  the  low  tension  oil  switches  are  located  in  structures 
built  up  of  concrete  slabs  and  steel  framing.  The  high  tension  bus  consists  of  i-inch 
copper  tubes,  supported  on  a  steel  structure  of  latticed  girders,  which  also  carries 
the  selector  switches. 

Transformers.  The  transformers  are  arranged  in  four  banks  of  three  each. 
They  are  of  2000  K.W.  capacity  oil-insulated,  water-cooled,  and  step  up  the  gener- 
ator voltage  to  44,000.  By  means  of  multiple  connections,  the  additional  ratios  of 
550/10,000  and  1100/22,000  volts  may  be  obtained.  Provision  is  also  made  inside 
of  the  transformer  tank  to  secure  1900,  2000,  and  2100  volts. 


FIG.  8. — Wiring  Diagram,  Great  Falls  Plant,  Southern  Power  Company. 


With  a  temperature  rise  not  exceeding  60°  C.,  a  circulation  of  4  gallons  of  water 
per  minute  at  full  load  is  required,  while  with  5  gallons  of  water  per  minute,  and 
1.25  load,  the  temperature  will  not  exceed  55°  C.  over  that  of  the  intake  water, 
during  continuous  operation. 


TYPICAL  HYDROELECTRIC  PLANTS 
The  guarantees  are  as  follows: 


359 


Power  factor  

100 

o-95 

9o 

2.4 

85 
2.9 

Regulation,  per  cent  

Load 
Efficie 

i 
96.4 

i 

98 

i 

98-3 

Full 
98.4 

il 
98.3 

ncy,  per  cent   .        

The  transformers  are  located  in  compartments  resting  upon  rollers  on  rails,  in 
front  of  which  is  a  transfer  table,  by  which  means  they  may  be  moved  into  the 
generating  room  where  they  are  handled  by  the  overhead  crane. 


FIG.  9. — High  Tension  Switch  Room,  Southern  Power  Company. 

All  transformers  are  connected  to  a  pipe  system,  by  which  carbonic  acid  gas 
may  be  admitted  in  case  of  fire.  The  carbonic  acid  generator  and  pressure  tank  are 
located  in  the  basement  of  the  transformer  house.  Connections  are  also  made  to 
the  upper  floor,  so  that  in  case  of  fire,  the  various  apparatus  may  be  attacked  by 
the  gas 

Oil  to  the  transformers  may  be  supplied  by  gravity  or  under  pressure,  for  which 
purpose  an  electric  operated  triplex  pump  is  installed  in  the  basement.  The  cir- 
culating water  is  obtained  by  gravity  from  the  exciter  turbine  supply. 


360 


HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 


Protection.  In  order  to  partially  relieve  the  transformer  windings  of  excessive 
strain,  due  to  surges  in  the  line,  choke  coils  of  the  oil-insulated  type  are  placed  between 
the  transformers  and  their  respective  bus  oil  switch.  The  lightning  arresters  are 
of  the  single  pole,  low  equivalent  type. 


FIG.  10. — Solenoid  Operated  Oil  Switches. 

Transmission  Lines.  Current  is  transmitted  from  the  Catawba  station  to  near-by 
towns  at  11,000  volts.  The  poles  are  35  feet  long,  14  inches  at  the  butt,  and  7  inches 
at  the  top,  and  buried  5.5  feet  in  the  ground,  this  section  being  thoroughly  coated 
with  coal  tar.  The  line  running  to  Rock  Hill  consists  of  two  circuits  of  No.  o  hard 
drawn  copper  wire.  On  the  line  to  Charlotte  and  Fort  Mill,  aluminum  cables  of 
200,000  cm.  are  used.  The  poles  on  the  former  are  spaced  100  feet,  while  on  the 
latter,  150  feet  apart. 

The  whole  transmission  system,  with  the  exception  of  the  Rock  Hill,  Fort  Mill 
and  Yorkville  line,  is  being  changed  preparatory  for  transmission  at  44,000  volts, 
immediately  upon  completion  of  the  Great  Falls  station.  From  Great  Falls  to 
Catawba  station,  a  trunk  line  supported  on  steel  towers  is  being  built.  At  Catawba 


TYPICAL  HYDROELECTRIC  PLANTS. 


i  —  v, 


362  HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 

station,  a  transformer  house  is  being  erected  to  contain  32,ooo-K.W.,  11,000/44,000- 
volt  transformers,  with  suitable  switch  gear  for  running  the  two  stations  in  multiple. 

Both  primaries  and  secondaries  of  the  transformers  throughout  the  whole  system 
are  delta  connected.  By  this  arrangement,  the  line  voltage  may  be  raised,  should 
a  higher  one  be  deemed  advisable  in  the  future. 

Towers.  For  the  44,ooo-volt  main  circuit,  galvanized  two-circuit  steel  towers 
are  used.  They  are  of  the  Aermotor  twin  type  as  illustrated  in  the  chapter  on  steel 
towers. 

Each  half  is  joined  to  the  other  at  a  point  midway  between  base  and  top.  The 
corner  angles  of  each  half  are  3  by  3  by  three-sixteenths  inch,  while  the  two  lower 
inside  corner  members  are  3  by  3  by  one-eighth  inch  angle  iron.  The  two  halves 
are  joined  together  by  a  batten  plate.  The  width  of  the  base  in  the  direction  of  the 
line  is  13  feet  2  inches,  while  in  the  opposite  direction,  14  feet  6  inches.  The  cross- 
arm  brackets  are  of  2^  by  2^  by  one-eighth  inch  angle,  braced  by  2-inch  pipe. 
Upon  2-inch  pipe  insulator  pins  are  mounted  Thomas  insulators,  13  inches  high 
and  12  inches  diameter. 

A  six-strand  cable  with  a  hemp  core,  equivalent  to  No.  ooo,  is  used  for  the  main 
three-phase  circuit,  located  at  the  corners  of  the  triangle-shaped  towers,  6  feet  on 
the  leg. 

The  spacing  of  the  towers  is  approximately  420  feet,  there  being  12  towers  to 
the  mile.  The  standard  tower  is  35  feet  high  from  the  ground  to  the  lowest  con- 
ductor; there  are  a  few  43  and  50- foot  towers.  They  weigh  2400,  3000,  and  3500 
pounds  respectively.  The  four  legs  of  the  twin  towers  are  bolted  to  angles  embedded 
in  a  concrete  footing. 

The  standard  35-foot  towers  stood  the  following  tests:  first,  a  horizontal  pull  of 
1000  pounds  applied  at  the  top  of  each  insulator  pin;  loads  were  applied  both  in  the 
direction  of  the  line  and  at  right  angles  thereto.  Second,  a  horizontal  pull  of  8000 
pounds  applied  across  the  two  apices  of  the  tower,  both  in  the  direction  and  at  right 
angles  to  same.  Third,  when  tested  to  destruction,  the  tower  collapsed  at  a  corrected 
pull  of  14,000  pounds  applied  across  apices  of  the  tower  in  the  direction  of  the  line. 

Financial  Aspects.  In  discussing  the  market  at  the  time  the  Southern  Power 
Company  was  organized,  the  field  of  distribution,  of  course,  was  well  considered. 
The  power  was  to  be  used  largely  for  the  operation  of  cotton  mills  which  possessed 
their  own  plants.  Investigation  showed  that  it  amounted  to  approximately 
200,000  HP.,  one-fourth  of  which  is  water  power. 

The  fundamental  requirements  for  all  power  developments  are,  a  sufficient  source 
of  power,  and  market  for  same,  and  necessary  capital.  To  make  the  development 
of  the  Southern  Power  Company's  system  a  paying  one,  of  course  thorough  investi- 
gations were  made,  and  the  following  is  an  abstract  by  Mr.  Fraser  on  this  subject.1 

Before  investing  in  the  sites,  a  careful  investigation  showed  the  average  cost  of 
power  to  be  in  the  neighborhood  of  $34  per  brake-horsepower-year  of  3366  hours; 
that,  although  a  few  of  the  larger  mills  had  this  cost  down  to  $30,  the  majority  of  the 

1  Some  Engineering  Features  of  the  Southern  Power  Company's  System,  by  J.  W.  Fraser.  Am.  Inst. 
E.  E.,  Atlantic  City,  N.J.,  June  30,  1908. 


TYPICAL  HYDROELECTRIC  PLANTS. 


363 


FIG.  12. — Main  Transmission  Line,  between  Great  Falls  and  Catawba. 


3^4 


HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 


smaller  mills  could  not  produce  power  for  much  less  than  $40.  With  coal  at  $3.50, 
power  could  not  be  distributed  for  less  than  $28,  even  from  large  central  steam 
stations.  Experience  acquired  from  the  Catawba  station  and  some  smaller  stations, 
to  the  records  of  which  access  was  had,  showed  a  fair  margin  of  safety  after  trans- 
mission and  other  losses  were  taken  into  account. 

True  it  is,  that  in  recommending  investment  in  these  sites,  it  had  to  be  considered 
that  although  the  electric  drive  had  demonstrated  in  some  instances  its  reliability, 

convenience  and  economy,  yet  the  unsatis- 
factory history  in  other  instances,  the  general 
impression  that  power  was  produced  for  much 
less  than  it  actually  cost,  and  the  fact  that 
mill  owners  were  averse  to  further  investment, 
would  make  the  sale  of  power  a  difficult 
matter.  Still,  the  main  question  which  inter- 
ested the  investor  was  the  cost  of  steam  power, 
for  prejudice  could  be  overcome  and  the  real 
cost  of  power  could  be  demonstrated.  In  a 
further  discussion  of  the  market,  it  is  found 
convenient  to  treat  it  under  separate  heads 
embodying  the  various  engineering  features. 

Frequency.  In  determining  what  fre- 
quency would  best  suit  the  market  con- 
ditions, the  following  had  to  be  taken  into 
consideration. 

a.  That  the  sixty-cycle  generators  at 
Catawba  station  and  some  8000  to  10,000  HP. 
in  induction  motors  receiving  power  from 
that  station  would  have  to  be  rewound  or 
exchanged  if  other  than  sixty  cycles  were  used, 
on  account  of  the  fact  that  separate  lines 
would  be  too  expensive  and  would  complicate 
matters.  Motor  generators  would  make  the 
cost  prohibitive,  because  of  the  large  number 
of  distributing  points. 


FIG.  13. — 50,000- volt  Insulator, 
Southern  Power  Company. 


b.  That  sixty-cycle  motors  to  a  total  of  approximately  8000  HP.  were  driving 
mills  in  the  vicinity  of  proposed  lines,  which  load  might  be  obtained,  provided  the 
frequency  was  the  same. 

c.  That  there  were  also  quite  a  few  small  city  plants  operating  at  sixty  cycles. 
At  present  this  might  not  amount  to  much,  but  the  growth  of  these  cities  had  to  be 
considered,  particularly  in  reference  to  arc  lighting.     In  three  years,  2500  arc  lights 
have  been  put  in  service,  and  if  motor  generators  had  had  to  be  installed,  the  cost  to 
small  mill  towns  would  have  been  excessive. 

d.  That  a  high  frequency  would  give  a  better  power  factor,  due  to  the  leading 
charging  current. 

e.  That  twenty-five-cycle  generators,  transformers  and  motors  would  cost  at  least 


TYPICAL  HYDROELECTRIC  PLANTS. 


365 


10  per  cent,  25  per  cent  and  10  per  cent  respectively,  more  than  sixty-cycle  generators, 
transformers  and  motors. 

f.  That  there  was  very  little  prospect  in  the  near  future  of  a  rotary  converter  or 
railway  load,  and  there  were  plenty  of  cotton  mills  in  the  district  covered  to  use  all  the 
power  which  could  be  generated  from  the  rivers. 

Against  the  above  is  the  extra  line  drop,  but  when  all  the  developments  are  com- 
pleted very  little  power  will  be  transmitted  more  than  forty  miles,  except  over  trunk 
lines,  where  the  drop  may  be  taken  care  of 
by  raising  the  generator  electromotive  force. 
For  instance,  the  voltage  at  Catawba  and  at 
Spartenburg,  two  centers  of  distribution,  can 
always  be  maintained  at  44,000  volts. 

These  conditions  seemed  to  favor  sixty 
cycles,  but  as  exact  figures  were  necessary  in 
this  case,  the  following  rough  calculation  was 
made.  The  saving  in  cost  of  generators  and 
transformers  amounted  to  $75,000,  and  if  the 
saving  in  copper  due  to  increased  power  factor 
is  added,  the  total  will  be  in  the  neighborhood 
of  $100,000. 

There  is  an  additional  loss  of  about  ten 
per  cent  of  the  loss  which  there  would  have 
been  at  25  cycles,  and  the  integrated  loss  over 
the  present  lines  when  fully  loaded  will  be  in 
the  neighborhood  of  27  per  cent.  In  power, 
this  amounts  to  10  per  cent  of  27  per  cent  of 
26,000  K.W.  =  700  K.W.,  which  at  $5  per 
K.W.  is  $3500.  Capitalized  at  6  per  cent 
this  amounts  to  $60,000  —  a  balance  of 
$40,000  in  favor  of  sixty  cycles.  It  is  possible 
that  a  very  careful  analysis  might  show  this 

loss  to  be  a  little  greater,  but  the  error  cannot  be  over  25  per  cent,  as  the  integrated 
loss  referred  to  has  been  taken  over  a  period  of  six  months  and  covers  losses  from 
generators  to  meters  on  load.  The  only  other  error  which  could  be  made  would  be 
in  estimating  the  line  drop,  when  the  present  lines  were  fully  loaded,  but  as  the  drop 
on  the  present  load  has  been  measured,  the  error  could  not  be  very  large. 

Considerations  a,  b  and  c  have  been  left  out  of  the  above  numerical  calcu- 
lation, but  might  easily  amount  to  several  times  the  figure  mentioned. 

Voltage.    Some  of  the  reasons  for  keeping  the  E.M.F.  as  low  as  44,000  volts  were : 

a.  That  44,ooo-volt  transformers  would  cost  from  18  per  cent  to  33  per  cent, 
depending  on  the  size,  less  than  for  66,ooo-volt  transformers. 

b.  That  transformers  and  switches  were  more  reliable  at  44,000  volts. 

c.  That  each  insulator  would  cost  about  80  per  cent  less. 

d.  That  line  operation  would  be  more  successful. 

e.  That  smaller  transformer  stations  could  be  built. 


FIG.    14. — Tower  used  for  Lines  in 
Cities,  Southern  Power  Company. 


366  HYDROELECTRIC  DEVELOPMENTS  AND  ENGINEERING. 

It  was  estimated  that  the  extra  copper  to  give  the  same  drop  over  the  entire  system 
at  44,000  volts  as  compared  with  66,000  volts  would  not  exceed  the  extra  cost  of  trans- 
formers, insulators,  substations,  switches  and  other  apparatus.  The  estimate  proved 
correct.  With  the  present  3o,ooo-HP.  load  there  are  on  the  system  72,000  K.W.  in 
step-up  and  step-down  transformers,  and  the  additional  cost,  if  66,ooo-volt  trans- 
formers had  been  used,  would  have  been  $64,000;  additional  cost  of  30,000  insulators 
at  eighty  cents,  $24,000;  additional  cost  of  thirty  66,000- volt  substations,  i.e.,  20  per 
cent  on  $125,000,  $25,000;  additional  cost  of  step-up  transformer  stations,  i.e.,  10  per 
cent  on  $200,000,  $20,000;  a  total  of  $133,000.  Against  this  is  the  saving  in  copper  in 
the  transmission  line  had  the  higher  electromotive  force  been  used,  roughly,  50  per 
cent,  $130,000. 

This  shows  a  saving  of  only  $3000,  but  the  present  lines  will  carry  a  great  deal 
more  power  than  they  are  now  carrying,  which  will  increase  this  amount  materially. 

One  only,  of  those  proposed,  stands  out  as  an  exception,  the  trunk  line  running 
from  Great  Falls  to  Spartenburg  and  thence  to  Greenville,  about  100  miles  in  length. 
This  line,  now  under  construction,  will  be  so  built  that  when  overloaded  at  44,000 
volts  delivered  E.M.F.  can  be  changed  to  88,000  volts  (i.e.,  100,000  volts  at  generating 
station).  This  will  be  accomplished  at  a  very  small  additional  expense,  by  mounting 
pins  and  insulators,  similar  to  those  now  used  on  our  wood  pole  lines,  on  the  towers, 
for  after  conversion  to  a  higher  E.M.F.,  these  pins  and  insulators  can  be  used  on 
44,ooo-volt  lines,  or  this  line  may  be  permanently  used  for  local  distribution.  The 
intention  is,  that  this  88,ooo-volt  trunk  line  will  not  be  tapped  at  any  point  except 
Spartenburg.  This  could  be  done  more  easily  by  using  ioo,ooo-volt  suspension  type 
insulators,  but  it  is  felt  that  by  the  time  it  is  necessary  to  change  to  the  higher  E.M.F., 
there  may  be  enough  improvement  made  in  these  insulators  to  warrant  the  extra 
expense  which  would  be  then  incurred. 

Transmission  Lines.  Further  examination  of  the  transmission  line  map  shows 
that  two-thirds  of  the  obtainable  power  is  in  the  neighborhood  of  the  Great  Falls 
development,  which  position  was  selected  as  a  main  switching  station;  the  idea 
being,  to  mass  the  output  of  Great  Falls,  Fishing  Creek,  Rocky  Creek  and  Rich  Hill 
at  this  point  on  outdoor  bus  bars,  and  control  the  line  switches  from  the  operating 
room  in  this  station. 

The  generators  and  transformers  were  designed  to  operate  continuously  at  85  per 
cent  power  factor  to  take  care  of  an  induction  motor  load,  and  at  115  per  cent  normal 
E.M.F.  to  take  care  of  line  drop  as  the  load  increased.  The  main  trunk  line,  from 
Great  Falls  to  Catawba  station,  will  take  care  of  20,000  K.W.  at  85  per  cent  power 
factor,  with  a  line  drop  of  13.5  per  cent  and  a  loss  of  7.25  per  cent.  This  represents 
the  economical  section  of  copper  at  twenty  cents  per  pound  with  power  costing 
$5  per  K.W.  year. 

It  should  be  pointed  out,  before  leaving  the  subject  of  transmission  lines,  that  the 
impossibility  of  making  contracts  with  mill  owners  on  account  of  their  skepticism 
with  regard  to  electric  drive,  before  the  greater  part  of  the  present  lines  were  actually 
built,  made  the  estimate  on  the  amount  of  power  to  be  sold  in  any  one  -territory  so 
difficult,  that  the  location  and  size  of  transmission  lines  could  not  be  determined  even 


TYPICAL  HYDROELECTRIC  PLANTS.  367 

approximately.     In  other  words,  where  and  in  what  amounts  power  was  to  be  sold 
was  a  very  uncertain  matter. 

This  brought  up  the  question  of  wood  pole  lines  versus  steel  towers.  A  little 
consideration  showed,  that  if  the  cost  of  towers  per  additional  foot  in  height  erected, 
was  seven  dollars,  and  copper  at  twenty  cents  per  pound,  a  No.  o  Brown  &  Sharp 
gauge  would  be  the  smallest  wire  which  could  be  strung  economically  on  account  of 
the  increased  sag  in  wires  below  this  size  for  5oo-foot  spans;  that  a  single  circuit 
tower  line  would  cost  approximately  twice  as  much  as  a  pole  line  and  would  last 
probably  twice  as  long;  that  a  double  circuit  tower  line  would  cost  very  little  more 
than  a  double  pole  line;  and  that  it  would  be  more  economical  for  cotton  mills  to  shut 
down  for  a  small  percentage  of  time,  than  to  pay  the  additional  price  for  power  which 
would  be  necessary  to  cover  the  extra  expenditure  for  steel  tower  lines.  It  therefore 
seemed  good  practice  to  build  main  trunk  lines  of  steel  towers,  and  all  single  lines 
below  No.  o  gauge,  of  wooden  poles. 

Secondary  Power.  From  government  records  and  from  six  years  of  gaug- 
ings  before  the  completion  of  the  Catawba  plant,  together  with  two  years'  operating 
experience,  the  flow  of  the  Catawba  River  had  been  pretty  well  determined. 

The  question  which  presented  itself  most  forcibly  was,  whether  to  develop  the 
average  minimum  twelve  months'  flow  or  to  develop  for  ten  months,  eight  months 
or  less,  and  to  supplement  with  steam  power;  a  problem  which  has  to  be  determined 
by  the  first  cost  of  development  and  by  local  market  conditions. 

In  following  calculations  where  the  cost  of  primary  and  secondary  power  is 
taken  at  a  fixed  rate,  the  intention  is  not  to  convey  the  idea  that  these  are  actual 
figures,  but  relative  figures  which  will  serve  the  purpose  of  this  paper. 

There  are  many  different  solutions  to  the  problem  of  ascertaining  the  amount  of 
secondary  power  which  may  be  economically  developed.  At  one  of  our  develop- 
ments, it  was  found  that  the  average  minimum  primary  power  was  in  the  neighbor- 
hood of  16,000  K.W.,  and  that  the  increase  per  month  of  secondary  power  was  in 
the  neighborhood  of  twelve  and  one-half  per  cent,  i.e.,  2000  K.W.  per  month. 

In  other  words,  if  secondary  power  was  to  be  developed  for  eight  months'  sale, 
the  total  development  of  primary  and  secondary  power  would  be  24,000  K.W.  If 
this  secondary  power  can  be  sold  without  an  auxiliary  steam  plant,  the  amount  of 
secondary  power  which  may  be  developed  economically  depends  only  upon  whether 
or  not  the  price  received  for  such  power  will  cover  interest  and  profit  on  the  invest- 
ment; that  is,  the  investment  which  is  over  and  above  that  for  developing  primary 
power;  but  if  a  steam  plant  has  to  be  maintained,  the  amount  of  secondary  power  to 
be  developed  depends  also  on  the  cost  of  steam  power.  It  is  very  clear  that  the  cost 
of  secondary  power  is  practically  the  same  whether  it  is  sold  for  eleven  months  or 
one  month.  With  this  cost,  say  at  $10  per  HP.  delivered,  steam  at  $28  per  HP.  year 
($6  interest  and  depreciation,  $22  for  coal,  operating  expenses,  etc.),  if  interest  and 
depreciation  on  the  steam  plant  is  entirely  chargeable  to  the  months  when  steam 
plant  is  in  operation,  then 

Cost  of  steam  power  per  month  =1.83  +  6/x 
when  x  =  the  number  of  months  in  operation. 


368  HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 

Amount  of  secondary  power  to  be  developed  =  16,000  kilowatts  X  12.5^/100  = 

2OOOX. 

Cost  of  steam-secondary 

=   20OOX    (1.83    +  6/x)x    +   2OOOX   X    IO 
=  2000      l.SX2    +  6X 


If  power  is  selling  at  $20,  profit 

=  (200OX  20  —  {2000  (i.S^x2  +  i6x)l 

—  2000    (20X    —   I.&3X2     -   l6x). 


For  max.  dy/dx  —  $.66x  —  3.66^  —  4 
x  =  i.i  month. 

On  this  basis,  maximum  profit  would  be  made  on  2000  K.W.  secondary  develop- 
ment. 

A  more  practical  method  under  existing  conditions  seems  to  be  to  charge  the 
interest  and  depreciation  of  steam  plant  to  the  operating  expenses  of  the  system, 
inasmuch  as  the  steam  plant  is  an  insurance  against  a  partial  shut-down  and  makes 
spare  units  unnecessary,  and  in  the  case  of  steam  turbines,  when  run  as  synchronous 
motors,  saves  copper  because  it  brings  up  the  power  factor.  The  above  equation 
now  becomes: 

Cost  of  steam  +  secondary 

=  2000JC   (1.83^)    +   2000X   X    IO) 
=  2OOO    (l.S^X2    +   IOX). 


Profit 

=  200O  X  20  —  (2OOO  (1.83^  + 
=  2000  (2OX  —  I.S^X  —  IOX~) 
=  2000  (lOX  —  1.  83^) 

(For  max.)  dy/dx  =  3.66^  —  10 
x  =2  -3/4- 

Maximum  profit  on  this  basis  would  be  made  on  5500-K.W  (35  per  cent)  secondary 
development. 

Had  $24.50  been  taken  as  the  selling  price  of  power,  x  would  equal  four  months, 
or  the  total  development  should  be  made  for  150  per  cent  of  mean  average  low  water. 
Although  power  from  hydroelectric  plants  has  been  selling  in  the  Carolinas  for  less 
than  this  latter  figure,  there  is  no  doubt  that  reliable  service  demands  this  price. 


TYPICAL  HYDROELECTRIC  PLANTS.  369 

THE    NECAXA   PLANT,    MEXICAN    LIGHT   AND    POWER    CO. 

Mexico,  a  country  where  industry  is  growing  rapidly,  recognized  at  an  early  date 
the  advantage  of  utilizing  high  water  falls  and  transmitting  the  power  by  high  tension 
lines  to  the  centers  of  consumers.  As  early  as  igoi,1  a  5o-foot  fall  of  the  Lerma 
River  at  Juanacatalan  was  utilized  by  belt-driven,  single-phase  turbine  generators, 
and  the  energy  transmitted  on  iron  poles  over  a  distance  of  17  miles  to  the  city  of 
Guadalajara,  the  potential  being  5000  volts.  In  the  year  1895,  a  io,ooo-volt  trans- 
mission line  was  installed,  transmitting  the  energy  of  the  waterfall  at  Regla  to 
Pachuca,  where  it  was  used  in  the  cities  and  mills,  as  well  as  for  operating  the  mines 
of  the  Rio  del  Monte  Company.  The  generating  voltage  was  700,  three-phase. 
The  turbines,  of  which  there  are  five,  are  of  the  impulse  type,  operating  under  an 
effective  head  of  800  feet. 

The  Guanajuato  Power  and  Electric  Company  erected  at  Zamora,  in  1903,  a 
power  plant  which  utilized  a  head  of  320  feet.  The  water  was  supplied  by  a  canal 
5  miles  long  and  a  penstock  3300  feet  in  length.  Two  1125  HP.  impulse  wheels  are 
connected  to  a  I25O-K.W.  three-phase,  6o-cycle  generator  running  at  200  R.P.M. 
By  a  step-up  transformer  the  voltage  was  increased  to  60,000  and  the  power  trans- 
mitted over  a  line  no  miles  long  to  Guanajuato,  supplying  the  silver  mines  and  mills. 
The  line  is  40  to  50  feet  above  the  ground,  supported  on  galvanized  steel  towers 
placed  450  feet  apart  on  the  average,  the  longest  span  being  1500  feet. 

Necaxa  Plant.  The  largest  and  most  prominent  of  Mexican  plants  now  in 
operation  is  that  of  the  Mexican  Light  and  Power  Company  at  Necaxa,  utilizing 
the  waters  of  the  Tenango  and  Necaxa  rivers.2  It  is  designed  for  capacity  of 
20,000  HP.,  operating  under  a  static  head  of  1452  feet,  and  transmitting  energy  at 
60,000  volts  to  the  City  of  Mexico  and  the  gold  mines  of  El  Oro.  This  transmission 
line  is  160  miles  in  length. 

There  is  in  view,  besides  the  above,  the  utilization  of  the  tailrace  and  other  sources 
under  a  head  of  700  feet,  also  developing  20,000  HP.  Should  there  be  a  demand  for 
more  power,  the  company  is  in  a  position  to  provide  for  some  30,000  HP.  additional, 
under  a  head  of  2100  feet.  If  this  is  ever  done,  it  is  proposed  to  increase  the  voltage 
from  60,000  to  80,000,  for  which  the  line  has  been  designed. 

As  the  power  plant  is  located  in  a  very  inaccessible  part  of  the  state  of  Puebla, 
to  facilitate  the  construction  of  the  plant,  it  was  necessary  to  build  many  roads  and 
trails  as  well  as  some  30  miles  of  railroads.  For  a  vertical  distance  of  1500  feet, 
the  machinery  and  other  material  had  to  be  lowered  by  cableways  down  steep  cliffs 
to  the  power  house.  The  cableways  were  capable  of  handling  15  tons.  Further- 
more, a  temporary  power  plant  had  to  be  built  with  two  5oo-HP.  Pelton  wheels  con- 
nected to  5oo-volt  direct  current  generators.  Engineering  camps  were  located  on  a 
mesa  1700  feet  above  the  power  house,  and  for  giving  shelter  to  the  working  4000 
Mexicans,  three  new  towns  were  built  to  replace  the  towns  flooded  by  the  reservoirs. 

1  Electric  Power  Developments  in  Mexico,  by  F.  O.  Blackwell.     Cassier's  Magazine,  July,  1905. 

2  "  The  Necaxa  Plant  of  The  Mexican  Light  and  Power  Co.,"  by  F.  S.  Pearson  and  F.  O.  Blackwell, 
Am.  Soc.  C.  E.,  Vol.  LVIII,  p.  37,  1907. 


TYPICAL  HYDROELECTRIC  PLANTS, 


371 


SECTION  B-B  TOP  VIEW 

FIG.  2.— General  View  of  Intake  for  Dam  No.  2,  Necaxa  Plant,  Mexico. 


372  HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 

Drainage  Area.  The  drainage  area  of  the  Tenango  and  Necaxa  rivers  is  a  portion 
of  the  plateau  on  which  the  City  of  Mexico  is  situated,  and  contains  227  square  miles. 
In  the  course  of  3  miles  the  water  drops  through  the  several  falls,  ranging  from  300  to 
800  feet,  some  3000  feet.  The  combined  average  flow  throughout  these  rivers  is 
245  cubic  feet  per  second,  while  the  minimum,  35,  and  maximum,  3000  cubic  feet,  is 
reached  only  at  certain  periods  of  the  year.  The  average  flow  for  a  period  of  seven 
years  was  350  cubic  feet  per  second. 

The  water  of  the  Tenango  is  diverted  into  the  Necaxa  by  means  of  a  4o-foot  dam 
and  a  3ooo-foot  tunnel,  9  feet  high  and  12  feet  wide.  The  tunnel  has  a  pitch  of 
4  feet  in  1000,  and  is  sufficient  to  carry  all  except  extreme  flood  water.  There  are 
several  storage  basins  on  the  Necaxa;  the  one  furthest  down  the  stream  is  the  Necaxa, 
having  a  capacity  of  one  billion  five  hundred  and  eighty-five  million  cubic  feet. 
Above  the  Tenango  tunnel  are  the  Texcopa,  of  six  hundred  and  forty-two  million, 
and  the  Laguna  Reservoir,  of  seven  hundred  million  cubic  feet  capacity. 

It  is  proposed  to  increase  the  latter  reservoir  to  a  capacity  of  2450  cubic  feet. 
This  will  be  accomplished  by  diverting  Los  Rayos  and  its  tributaries  into  the  reser- 
voir. This  storage  capacity  will  then  amount  to  four  billion  six  hundred  million 
cubic  feet,  and  will  be  ample  to  provide  the  requisite  average  for  many  years. 

Dams.  Owing  to  the  volcanic  origin  of  the  country,  it  was  not  advisable  to  con- 
struct masonry  dams.  For  this  purpose,  earth  dams  were  constructed  by  the  hydrau- 
lic fill  method,  utilizing  water  heads  up  to  400  feet.  The  Necaxa  dam'is  180  feet  high, 
with  a  thickness  of  95  feet  at  the  base  and  54  feet  at  the  crown,  the  latter  being 
1276  feet  long.  The  slope  on  the  upstream  side  is  3  to  i,  and  on  the  downstream 
side,  2  to  i.  The  faces  are  covered  with  broken  stone  60  feet  thick  at  the  bottom 
and  1 8  feet  at  the  crown.  Two  million  cubic  yards  of  material  were  used  in  its 
construction.  For  method  of  construction  of  this  dam,  see  Chapter  III,  Dams. 

The  Texcopa  dam  is  174  feet  high  and  1190  feet  long  at  the  top.  The  thickness 
at  the  base,  905  feet.  It  was  built  by  the  same  scheme  as  the  former.  The  present 
Laguna  dam  is  40  feet  high  and  has  a  length  of  400  feet.  On  the  north  side  of  the 
Necaxa  dam  is  provided  a  spillway;  on  the  southern  side  of  the  dam  are  located  the 
penstock  connections. 

Penstocks.  The  penstocks,  of  which  there  are  two,  are  supplied  through  two 
vertical  risers,  divided  into  five  stages  (see  Fig.  2).  Each  stage  is  provided  with 
a  rack,  screen  and  flood  gate.  Because  of  the  variable  quantity  of  water  stored  in 
the  dam,  this  system  of  stages  gives  a  simple  method  of  operating  the  flood  gates 
under  low  head  of  not  more  than  26  feet.  The  vertical  risers  are  located  on  the 
upstream  side  of  the  dam  in  a  tower-like  structure  made  of  concrete. 

All  racks  and  screens  are  located  in  pockets  in  this  structure,  and  are  easily 
cleaned  and  removed.  The  penstocks  have  a  diameter  of  8  feet  and  are  made  of 
three-eighths-inch  riveted  steel.  They  go  through  the  Necaxa  tunnel,  where  they  are 
provided  with  waste  valves.  From  here  the  pipe  is  reduced  to  6  feet  and  continues 
downstream  for  2200  feet  through  tunnels  and  over  valleys.  In  this  run  there  were 
about  800  feet  of  tunnels  cut. 

Near  the  first  Necaxa  Fall,  each  penstock  joins  a  reservoir  22  feet  long  and  7  feet 


TYPICAL  HYDROELECTRIC  PLANTS. 


373 


in  diameter.  From  each  of  these  two  reservoirs  lead  three  3o-inch  penstocks  through 
an  inclined  tunnel  down  to  the  power  house.  Near  the  junction  of  the  3o-inch  pipes 
and  reservoirs  is  connected  to  each  of  the  30-inch  pipes  a  3o-inch  air  pipe  extending 
310  feet  up  a  mountain  slope  to  an  elevation  above  the  top  of  the  dam.  All  penstocks 
are  provided  with  gates  at  the  reservoir  and  a  central  gate  separated  into  two  halves, 
so  that  either  half  can  be  shut  down  without  interfering  with  the  other.  The  30-inch 
^penstocks  are  provided  with  pack  slip  joints,  while  the  6-foot  pipes  are  supplied 
with  expansion  joints  of  the  diaphragm  type. 


FIG.  3. — Dam  and  Penstock,  Necaxa  Plant,  Mexico. 

When  the  plant  is  running  at  normal  full  load,  the  velocity  in  the  6-foot  penstocks 
is  7.5  feet,  and  in  the  30-inch  penstock  is  15  feet  per  second.  When  running  under 
extreme  overload,  the  velocity  of  the  water  in  the  3O-inch  pipes  is  18  feet. 

While  the  two  6-foot  penstocks  are  of  riveted  steel,  the  six  3o-inch  penstocks  are 
of  seamless  weld  tubes.  They  were  shipped  from  Germany  in  sections  of  29.5-foot 
lengths,  and  are  provided  with  flared  ends  and  loose,  movable  flanges  of  special 
design.  The  inside  diameter  of  the  3O-inch  penstocks  at  the  power-house  end  is 


374 


HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 


29  inches.  The  thickness  of  these  tubes  varies  from  0.5  inch  to  0.95  inch.  Each 
of  the  six  3o-inch  penstocks  is  2460  feet  long;  the  length  of  upper  sections  is  1900 
feet.  They  run  through  two  parallel  tunnels,  each  being  13  feet  wide  and  10  feet 
high  and  run  on  an  incline  of  41  degrees. 

All  pipes  and  penstocks  are  supported  on  concrete  piers.  The  static  head,  with 
filled  reservoir,  is  1452  feet  at  the  turbine;  due  to  friction,  this  head  is  reduced  to 
between  1200  and  1300  feet. 


FIG.  4. — Power  House  of  the  Necaxa  Electric  Light  and  Power  Company.     In  Background 

2nd  Necaxa  Falls,  740  feet  High. 

Power-Plant  Building.  The  power  house  is  located  in  the  bottom  of  a  canyon 
740  feet  deep.  The  building  is  235  feet  long,  88  feet  wide,  and  37.5  feet  from  floor 
to  roof  truss. 

It  is  divided  in  the  middle  longitudinally  by  a  partition  wall,  separating  the 
generating  room  from  the  switching  and  transformer  room.  In  the  basement  of  the 
generating  room  are  the  turbines,  while  penstocks  enter  beneath  the  transformer 
room. 

The  whole  structure,  sub  and  superstructure,  is  of  concrete.  The  generating  room 
has  steel  columns  carrying  the  runways  for  a  4o-ton  electric-operated  crane  and  the  roof 
truss.  The  latter  is  carried  on  the  switching  room  side,  on  the  walls. 


376 


HYDROELECTRIC  DEVELOPMENTS  AND  ENGINEERING. 


Turbines  and  Regulators.  There  are  installed  six  impulse  wheels  mounted  on 
vertical  shafts,  each  having  a  rated  capacity  of  70x30  HP.  and  a  maximum  of  900x0  HP. 
The  wheels,  100  inches  in  diameter,  are  supplied  through  a  28-inch  gate  valve,  and 
make  300  R.P.M.  They  are  solid  cast  steel  disks,  to  which  are  bolted  24  steel  buckets. 

For  each  wheel  there  are  two  4^-inch  square  regulating  nozzles,  situated  dia- 
metrically opposite;  both  are  connected  by  a  single  automatically  operated  valve, 
which  opens  and  closes  the  nozzles  simultaneously.  This  arrangement  prevents  the 


FIG.  6. — Cross  Section  of  Necaxa  Power  Plant,  Mexico. 

possibility  of  water  hammer.  At  the  end  of  the  present  penstocks  in  the  power  house 
are  located  relief  valves.  The  maximum  quantity  of  water  for  each  wheel  is  adjusted 
by  the  governor,  by  means  of  a  by-pass,  which  is  adjusted  to  close  slowly  so  that  little 
water  will  be  wasted.  All  turbines  and  governors  were  supplied  by  Escher,  Wyss, 
Zurich,  Switzerland. 

Generators.  Each  turbine  is  connected  to  a  5ooo-K.W.,  three-phase  revolving 
field,  50-cycle,  4ooo-volt  alternator.  Two  of  these  alternators  are  provided  with  a 
6o-K.W.  exciter,  mounted  upon  an  extension  of  the  shaft.  Besides  this,  there  are 
two  25O-K.W.,  225-volt  induction  motor-driven  exciters.  For  ordinary  service,  these 
motor-driven  sets  are  used;  only  in  emergency  cases  are  the  exciters  on  the  generating 


TYPICAL  HYDROELECTRIC  PLANTS. 


377 


shaft  employed.  The  generators  and  motor-driven  exciters  were  supplied  by  the 
Siemens-Schuckert  Werke,  Berlin. 

Wiring  System.  There  is  a  high  and  low  tension  bus,  between  which  are  located 
the  transformers.  Sufficient  oil  and  disconnecting  switches  are  supplied  so  that  there 
will  be  a  continuity  of  service.  The  outgoing  lines  are  well  protected  with  lightning 
arresters. 

Switching  Room.  The  switching  room  has  two  floors,  the  lower  one  containing 
the  transformers,  high  tension  busses  and  lightning  arresters,  which  are  separated  by 


FIG.  7. — Interior  of  Necaxa  Plant,  Mexico. 


partition  walls  running  lengthwise.  The  upper  floor  contains  the  switchboard,  in 
front  of  which  is  a  gallery  overlooking  the  generating  room.  Here  are  also  located  the 
low-tension  and  high-tension  oil  switches,  between  which  are  the  low-tension  bus  bars. 
The  current  transformers  are  also  located  on  this  floor  (see  general  plan  of  power 
house).  At  one  end  of  this  floor  are  the  offices,  lockers,  etc. 

Transformers.  The  transformers  are  of  the  single-phase,  2ooo-K.W.,  General 
Electric  Company,  oil-cooled  water  circulating  type,  designed  to  step  the  generator 
voltage  from  4000  to  40,000/50,000/60,000.  To  facilitate  inspection  and  repair, 
the  transformers  may  be  wheeled  on  tracks  into  the  generating  room,  and  there  handled 
by  an  overhead  crane.  Each  transformer  compartment  is  provided  with  a  steel  bulk- 
head. 


378 


S 

c 
w 


^ 

U 

Ul 

1 

z 

cT 

X 

1  -^ 

ed 

z 

o 

O 

ij 

tn""L 

-1     CO 

Z 

H\l^l\l^ 

_-JXJ\|xl\ 

II 

c 

ja 

?    2 

<u 

i^H 

S  £ 

f* 

S 

(U 

o 

c 

Ul 

<o 

,2 

1 

en 

M) 


a, 

aJ 

S 


O 

h-l 
- 


TYPICAL  HYDROELECTRIC  PLANTS. 


379 


FIG.  9. — 40-foot  Transmission  Tower,  Necaxa,  Mexico.  Similar  Type  of  Tower  is  used  in 
the  8o,ooo-volt  Transmission  Line  between  Rio  das  Lages  and  Rio  de  Janairo  of  the 
Rio  de  Janairo  Tramway,  Light  and  Power  Company,  South  America. 


380 


HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 


Oil  Switches.  The  oil  switches,  both  high  and  low  tension,  are  of  the  General 
Electric  Company,  remote-control  type  and  operated  from  a  control  bench,  in  front  of 
the  switchboard,  provided  with  a  dummy  bus  bar  system. 

Switchboard.  The  switchboard  is  built  of  ornamental  ironwork;  the  panels  are  of 
enameled  slate  and  equipped  with  the  necessary  indicating  and  recording  instruments 
as  employed  in  most  up-to-date  power-house  practice. 

Transmission  System.  The  present  transmission  system  consists  of  two  tower 
lines  of  two  circuits  each,  running  from  the  power  plant  to  the  City  of  Mexico,  some 
94  miles,  and  from  here  to  El  Oro  mines,  a  distance  of  75  miles.  It  has  been  designed 


FIG.  10. — Necaxa  Transmission  Lines  towards  City  of  Mexico. 

with  an  eight  per  cent  line  loss  between  the  power  house  and  Mexico,  and  a  5  per 
cent  loss  between  Mexico  and  El  Oro,  thus  giving  a  total  line  loss  of  13  per  cent  at 
100  per  cent  power  factor  and  60,000- volt  transmission. 

Towers.  The  towers  are  of  the  four-legged  A-frame  type,  14  feet  square  at  the 
bottom  and  12  feet  wide  at  the  top.  They  stick  6  feet  into  the  ground,  and  are  built 
of  angle  iron,  heavily  galvanized,  and  were  shipped  knocked  down.  The  circuits 
are  supported  on  porcelain  insulators  40  and  46  feet  above  the  ground.  The  towers  are 
designed  to  stand  a  horizontal  side  stress  of  1650  pounds  per  insulator  pin,  or  10,000 
pounds  per  tower,  and  are  calculated  to  withstand  a  wind  velocity  of  100  M.P.H.  The 
average  span  is  500  feet,  but  spans  as  high  as  1500  feet  were  installed,  using  special 
structures. 

Insulators.  The  insulators  are  made  of  three  parts,  cemented  together  on  the  field. 
They  were  tested  when  wet,  at  the  manufacturer's, The  R.Thomas  and  Sons  Company, 
East  Liverpool,  Ohio,  for  a  potential  of  60,000  volts.  After  being  assembled  in  the 


TYPICAL  HYDROELECTRIC  PLANTS.  381 

field,  they  were  tested  at  120,000  volts.  The  insulators  are  carried  on  steel  pins  set  in 
drop-forged  sockets. 

Conductors.  The  conductors  are  six-strand  copper  cables,  one-half  inch  in  diam- 
eter, with  hemp  centers,  and  have  a  strength  of  60,000  pounds  and  an  elastic  limit  of 
40,000  per  square  inch.  Joints  are  made  with  i8-inch  copper  sleeve  every  3000  feet. 

Substation.  There  are  two  step-down  transformer  stations,  one  at  Mexico  City 
and  the  other  at  El  Oro.  The  substation  at  the  City  of  Mexico  is  210  feet  long  and 
65  feet  wide.  It  is  arranged  to  accommodate  fifteen  i8oo-K.W.,  single-phase,  oil- 
cooled  transformers.  They  are  placed  in  fireproof  compartments  and  can  be  removed 
on  tracks  and  handled  by  a  crane.  The  step-down  transformers  are  designed  to  give 


FIG.  ii. — Substation  at  El  Oro,  Necaxa  Light  and  Power  Company,  Mexico. 

1500/3000/6000  volts  on  the  low-tension  side.  The  general  arrangement  of  the 
substation  is  similar  to  the  switching  and  transformer  room  at  the  main  power  house. 
This  station  is  run  in  connection  with  an  old  Siemens-Halske  steam  plant,  to  which 
four  Curtis  turbo-generator  units,  of  500  K.W.  each,  have  been  added. 

The  substation  at  El  Oro  is  115  feet  long  and  59  feet  wide.  It  contains  nine 
i8oo-K.W.  transformers.  The  arrangement  of  the  transformers  is  similar  to  that 
in  the  City  of  Mexico.  The  distribution  from  the  substation  to  the  mines  at  El  Oro 
is  3000  and  6000  volts. 

Both  substations  are  well  provided  with  up-to-date  switch  gear  and  lightning 
arresters.  At  the  power  house  as  well  as  at  the  substations,  the  circuit  breakers  are 
so  arranged  as  to  automatically  cut  out  any  section  which  may  become  damaged 
by  lightning. 


382  HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 

HYDROELECTRIC   PLANT,    KYKKELSRUD-HAFSLUND,   NORWAY.1 

Norway  is  one  of  the  richest  countries  in  Europe  in  water  resources.  In  the  last 
ten  years  many  plants  have  been  erected  to  utilize  these  waters.  Most  of  the  power 
is  used  for  industrial  purposes,  particularly  for  the  iron  industry  and  also  agricultural 
purposes.  To  utilize  the  water  of  the  river  Glommen,  the  largest  river  in  Norway, 
the  Aktieselskabet  Glommens  Traesliberi  in  Christiana  was  formed.  The  well- 
known  Schuckert  Company  of  Nuremburg  designed  and  constructed  a  plant  at 
Hafslund,  and  later,  one  at  Kykkelsrud,  which  is  38  miles  southeast  of  Christiana. 
Both  plants  utilize  water  from  the  same  river  and  are  about  25  miles  apart.  The 
first  equipment  of  the  Hafslund  plant  was  put  into  operation  in  1899,  while  the 
equipment  at  Kykkelsrud  was  put  into  operation  in  1903.  In  1907  a  50,000- volt 
transmission  system  was  installed  to  assist  the  plant  at  Hafslund  with  8000  K.W. 

At  the  same  time,  additional  equipments  were  added  to  both  plants,  and  the  two 
to-day  run  in  parallel. 

The  river  Glommen  flows  in  a  southerly  direction  and  empties  into  Christiana 
Fjord.  Like  most  Norwegian  rivers,  it  has  many  tributaries  of  streams  and  lakes. 
It  has  a  drainage  area  of  16,000  square  miles.  The  highest  tributary  is  8400  feet 
above  sea  level,  while  the  largest  lake  tributary,  Mjosen,  has  an  area  of  148  square 
miles.  The  area  of  the  lake  tributaries  is  3  per  cent  of  the  entire  drainage  area  of 
the  Glommen.  From  the  data  given  it  is  seen  that  this  one  river  furnishes  an  abund- 
ant water  supply  for  power  purposes,  when  advantage  is  taken  of  the  many  lakes  as 
natural  -storage  basins.  At  present,  the  largest  plant  is  utilizing  the  waterfall  at 
Kykkelsrud  under  an  effective  head  of  some  60  feet,  and  when  the  ultimate  equipment 
is  reached,  35,000  HP.  will  be  developed. 

Headrace.  On  the  left  side  of  the  Kykkelsrud  Falls,  the  river  Glommen  is  tapped 
by  an  open  canal  about  40  feet  deep,  3300  feet  long,  which  leads  the  water  to  a  forebay 
in  the  rear  of  the  power  plant,  which  is  located  in  a  cove  some  3500  feet  below  the 
falls.  As  the  river  is  used  for  floating  logs  down  from  the  mountains,  the  inlet  to 
the  canal  is  protected  by  a  floating  deflector.  The  deflector  is  made  up  of  wooden 
lattice  work  and  extends  some  three  meters  into  the  water.  A  wooden  deflecting 
structure  was  chosen  because  of  the  unknown  effect  the  logs  might  have  at  certain 
seasons  of  the  year. 

At  the  entrance  of  the  canal  are  two  sluice  gates,  separated  by  a  pier.  Each 
sluice  gate  is  divided  into  five  sections  to  facilitate  the  regulation  of  the  water.  They 
may  be  operated  by  hand  individually  or  by  electric  motors  collectively,  for  which 
two  i8-HP.  motors  are  installed.  When  the  gates  are  wide  open,  the  opening  has 
an  area  of  1500  square  feet,  giving  the  water  a  velocity  of  4.1  feet  per  second.  If 
necessary,  this  opening  can  be  increased  by  removing  some  stop  logs. 

As  stated,  the  forebay  is  located  in  the  rear  of  the  power  house  and  is  420  feet 
long.  It  is  provided  at  the  end  with  three  sluice  gates  to  let  out  sand,  gravel,  and 
anchor  ice.  One  of  the  gates  is  used  to  let  out  floating  material.  The  spillway  is 

1   Die   Ausnutzung  der  Wasserkrafte  des   Glommens  bei  Kykkelsrud  (Norwegen),  by  I.  H.  Kinbach, 
Miinchen.      Zeitschrift  des  Vereines  deutscher  Ingenieure. 


CTJ 

J3 

u 

d> 

.s 


386 


HYDROELECTRIC  DEVELOPMENTS  AND  ENGINEERING. 


330  feet  wide.  The  penstocks  leave  the  forebay  at  right  angles,  and  are  provided 
with  fine  screens  and  sluice  gates.  The  gates  are  operated  from  the  top  of  the  forebay 
wall,  where  also  the  cleaning  of  the  racks  is  accomplished.  As  the  forebay  wall  is 
only  45  feet  away  from  the  rear  wall  of  the  power  house,  the  penstocks  have  a  short 
run,  being  only  100  feet  long. 

Power  House.  The  power  house  was  originally  designed  to  accommodate  four  main 
turbine  units  and  two  exciter  units.  The  general  arrangement  consists  of  a  generating 
room  150  feet  long  and  50  feet  wide,  set  directly  over  the  turbine  pits,  which  are  25  feet 
wide  and  15  feet  deep.  Behind  the  generating  room  is  the  transformer  and  switching 
room;  the  transformer  room  floor  is  about  5  feet  below  the  main  generating  room 
floor.  The  switchboard  gallery  is  16.5  feet  above  the  main  generating  room  floor. 


FIG.  4. — Power  Plant,  Kykkelsrud,  Norway. 


In  the  middle  of  the  rear,  adjoining  the  transformer  room  and  beneath  the  street 
level,  is  the  pump  room. 

The  arrangement  of  the  windows,  pilasters  and  location  of  generating  units  is 
symmetrical.  There  are  five  bays,  the  middle  one  containing  two  28o-HP.  exciter 
units  and  the  controlling  switchboards.  On  each  side  of  the  middle  section  are  two 
generators.  The  entire  interior  is  finished  off  in  light  color,  the  floor  finished  with 
diamond-shaped  tile.  The  generating  room  is  provided  with  abundant  light  and 
ventilation. 

Turbines.  Owing  to  the  great  fluctuation  in  the  water  level  (the  head  varies  from 
40  to  64  feet),  it  was  decided  to  use  inclosed  Francis  turbines.  Of  the  first  installa- 
tion, one  main  and  two  exciter  turbines  were  furnished  by  Voith,  Heidemheim,  while 
the  other  main  unit  was  furnished  by  Escher  Wyss,  Zurich.  The  Voith  3OOO-HP. 


TYPICAL    HYDROELECTRIC    PLANTS. 


387 


turbine  was  designed  for  a  head  varying  from  52  to  62  feet  and  consuming  from 
670  to  530  cubic  feet  per  second,  and  running  with  a  speed  of  150  R.P.M. 

The  water  is  fed  to  the  turbine  with  a  velocity  of  9  feet  per  second  through  a 
9.8-foot  penstock  embedded  in  concrete.  Where  the  penstock  joins  the  turbine  casing, 
there  is  an  8.5-foot  hand-operated  geared  butterfly  valve.  The  turbine  casing  is  rec- 
tangular and  built  of  structural  steel.  The  inlet  of  the  spiral  casing  is  6.5  by  3.4  feet, 
thus  giving  a  velocity  to  the  water  of  9  feet  per  second.  The  velocity  of  the  water  at 
discharge  is  3.9  feet  per  second. 


FIG.  5. — Headrace,  Kykkelsrud  Plant,  Norway. 


The  vertical  shaft  of  the  turbine  is  12  inches  in  diameter  and  about  25  feet  long; 
on  top  of  this  is  coupled  the  shaft  of  the  generator.  The  weight  of  the  revolving  part 
is  32  tons  and  is  taken  up  in  a  step-bearing  running  under  an  oil  pressure  of 
220  pounds  per  square  inch.  The  regulation  of  the  turbines  is  accomplished  by  an 
hydraulically  operated  governor  and  works  in  conjunction  with  the  oil  pressure  in 
the  step  bearing. 

The  principal  difference  between  the  Escher  Wyss  and  the  Voith  turbine  is  that 
the  former  has  a  cylindrical  casing  and  vertical  moving  ring-gates,  while  the  latter 
has  a  spiral  turbine  casing  with  a  so-called  clam-shell  gate.  The  penstock  connec- 
tions and  butterfly  valves  are  the  same.  The  cylindrical  gate  is  operated  by  a  three- 
piston  arrangement,  worked  by  oil  pressure  controlled  by  the  hydraulic  governor. 
This  governor  is  similar  to  that  of  the  Voith  turbine  and  is  operated  by  gearing  from 


388 


HYDROELECTRIC    DEVELOPMENTS   AND    ENGINEERING. 


the  main  shaft.  The  guarantee  of  the  main  turbines,  from  their  manufacturers,  under 
a  head  of  52.5  feet,  is  75  per  c^nt  at  normal  speed,  150  R.P.M.  Keeping  the  speed 
constant,  and  a  head  variation  of  6.5  feet  up  or  down,  the  guarantee  efficiency  is 
72  per  cent. 

The  oil  pressure  for  the  turbines  is  supplied  by  two  motor-driven    pumps   pro- 
vided with  air  chambers  to  maintain  uniform  pressure.    Each  pump  has  a  capacity 


FIG.  6. — Interior  of  Kykkelsrud  Plant,  Norway. 


of  90  gallons  per  minute;  under  ordinary  conditions,  only  one  pump  is  in  operation. 
If  one  pump  is  out  of  commission,  the  other  starts  up  automatically. 

The  two  recently  installed  turbines  are  of  the  same  type  as  the  above  described, 
but  have  a  capacity  of  3750  HP.  each. 

Exciter  Units.  The  two  exciter  turbines  are  located  in  one  wheel  pit  and  are 
supplied  by  one  6.5-foot  penstock.  The  branches  to  the  turbines  are  4.1  feet  in 
diameter  and  are  fitted  with  butterfly  valves.  The  guarantee  of  these  turbines 
under  a  head  of  52.5  feet,  is  76  per  cent  running  at  a  speed  of  325  R.P.M.,  the  water 
consumption  being  60.8  cubic  feet  per  minute.  These  turbines  are  not  supplied  with 
oil  pressure  step  bearings,  because  the  oil  pressure  pumps  are  driven  by  current  from 


TYPICAL    HYDROELECTRIC    PLANTS. 


389 


the  exciters.     The  weight  of  the  revolving  part  of  the  turbines  is  taken  up  by  relief 
disks  in  the  turbine  casing. 

The  generator  shaft  is  coupled  directly  to  the  turbine  shaft.  The  exciter  is  wound 
for  115  volts,  1580  amperes,  giving  181.7  K.W.  They  also  supply  the  station  with 
light,  besides  running  the  oil  pressure  pumps. 


FIG.  7. — View  in  Rear  of  Switchboard,  Kykkelsrud  Plant,  Norway. 


Generators.  The  main  generators  of  the  first  equipment  are  5ooo-volt,  3-phase, 
5o-cycle,  4o-pole  revolving  field  type  and  have  a  2ooo-K.W.  capacity.  A  full  load 
test  was  run  continuously  for  48  hours,  and  no  part  showed  a  temperature  greater 
than  26°  C.  With  unity  power  factor,  the  efficiency  was  96  per  cent,  and  with  power 
factor  0.80  the  efficiency  was  94.8.  The  copper  loss  was  31  K.W.;  the  iron  loss  with 
unity  power  factor  was  16  K.W.;  with  power  factor  0.80,  was  21  K.W.  The  friction 
and  windage  loss  was  59  K.W.;  this  included  all  friction  losses  in  turbine  and  shaft. 
The  excitation  at  full  load  is  290  amperes. 

The  two  recently  installed  generators  are  of  the  same  type  and  make  (Siemens 
Schuckert  Werke)  as  the  above,  and  have  a  capacity  of  2500  K.W. 


390 


HYDROELECTRIC    DEVELOPMENTS    AND    ENGINEERING. 


Switchboard  Room.  The  switchboard  is  provided  for  four  generator  panels,  and 
two  panels  for  outgoing  feeders  located  on  a  gallery  16.5  feet  above  the  main  floor; 
the  exciter  switchboard  is  located  on  the  main  floor  directly  below  this  gallery. 

Each  generator  panel  has  a  voltmeter,  ammeter,  synchroscope  and  phase  lamps. 
The  lower  front  part  of  the  switchboard  has  hand  wheels  for  controlling  the  exciter 
current.  The  panel  for  the  2o,ooo-volt  outgoing  feeders  has  instruments  and  levers 
for  oil  switches  controlling  the  current.  As  there  are  two  complete  bus-bar  systems, 


FIG.  8. — Transformer  Room,  Kykkelsrud  Plant,  Norway. 


current  may  be  thrown  on  or  drawn  from  either.  These  bus  bars  as  well  as  all  5000- 
volt  apparatus  axe  mounted  upon  a  structural  steel  frame,  located  five  feet  in  the 
rear  of  the  switchboard,  thus  giving  a  passage  for  inspection  and  repairs.  The  oil 
switches  are  mounted  upon  the  top  of  this  framework  and  are  operated  by  levers 
(see  Fig.  7). 

The  current  from  the  generators  passes  through  fuses  placed  in  marble  compart- 
ments. There  are  three  transformers  for  each  generator  of  the  first  equipment  and 
they  are  located  in  the  basement  of  the  switchroom.  They  are  arranged  in  two  banks 
on  either  side  of  a  track  used  for  the  removal  of  the  transformers,  which  are  of  the  air- 


TYPICAL    HYDROELECTRIC    PLANTS. 


391 


cooled  oil  type,  950  K.  W.  each,  and  step  up  the  voltage  from  5000  to  20,000.  The 
transformer  tanks  are  surrounded  by  a  corrugated  iron  casing.  The  air  for  cooling 
comes  up  from  the  basement  beneath,  under  a  pressure  of  three-fourths  of  an 
inch. 

The  transformer  losses  for  full  load  at  unity  power  factor  are  19.75  K.W.  com- 
posed of  8.25  K.W.  iron  and  11.5  K.W.  copper  loss.  With  power  factor  unity  from 
half  to  full  load,  the  efficiency  is  constant,  98  per  cent.  For  continuous  full  load,  the 
temperature  of  the  transformer  oil  never  exceeds  40°  C. 


FIG.  9. — Interior  of  Substation  at  Hafslund,  Norway. 


Leads  from  the  transformer  go  to  the  high-tension  busses  located  in  a 
structural  steel  frame  on  the  same  floor  as  the  5ooo-volt  busses.  With  the 
extension  of  the  plant,  four  3-phase  transformers  of  225O-K.V.A.  capacity 
each,  have  been  installed.  They  are  of  the  water-cooled  oil  type  and  wound 
for  5 000/50,000- volt  transformation,  and  serve  exclusively  the  transmission  line  to 
Hafslund. 

Transmission  Line.  From  the  Kykkelsrud  power  house,  lead  2o,ooo-volt, 
3-phase  transmission  lines  toward  Christiana,  then  around  Christiana  Fjord  to 
Slemmestad,  where  the  last  substation  is  located.  Each  cable  has  a  cross  section 


392 


HYDROELECTRIC    DEVELOPMENTS   AND   ENGINEERING. 


of  50  square  mm.  for  a  distance  of  38  miles,  then  it  is  reduced  to  35  square  mm.  which 
runs  for  15  miles;  the  total  length  of  the  line  is  53  miles.  There  are  seven  substations 
along  the  line,  stepping  down  the  line  voltage  to  5000  for  local  distribution. 

The  lines  are  carried  on  wooden  poles  except  at  railroad  crossings  and  turns, 
where  structural  steel  poles  are  used.  This  line  was  put  into  operation  in  1903.  In 
1907  with  additional  plant  equipment,  a  5o,oco-volt  line  was  run  25  miles  southward 
to  assist  the  plant  at  Hafslund. 

This  line  is  also  run  on  wooden  poles  except  at  railroad  crossings  and  turns  where 
structural  steel  towers  are  used.  As  seen  in  Fig.  10,  the  steel  towers  have  a  close 
spacing,  and  in  addition,  the  tops  of  same  are  provided  with  triangular  steel  frames, 
which  ground  the  line  in  case  of  a  break.  These  precautions  were  required  by  the 
Public  Service  Commission.  The  wooden  poles  are  about  40  feet  long  and  stick 


FIG.  10. — 5o,ooo-volt  Transmission  Line,  Kykkelsrud  to  Hafslund,  Norway. 


about  6  feet  in  the  ground.  They  are  spaced  about  100  feet  apart.  The  cables  have 
a  cross  section  of  64  square  mm.  and  are  carried  on  porcelain  insulators  arranged 
in  triangular  form,  5.5  feet  on  a  leg;  the  cross  arm  is  of  steel.  The  insulators  are 
fastened  to  the  pin  by  hemp  and  shellac.  At  present  there  is  only  one  5o,ooo-volt 
line;  a  duplicate  one  is  projected  to  run  parallel  about  35  feet  from  it. 

Substation.  The  substation  at  Hafslund  is  equipped  with  four  aooo-K.V.A. 
transformers  of  the  water-cooled  oil  type,  and  are  designed  for  45,ooo/5ooo-volt 
step-down  transformation.  This  station  is  used  for  a  distributing  center  for  the 
power  from  Kykkelsrud  as  well  as  the  power  from  the  Hafslund  power  house.  The 
5o,ooo-volt  line  is  protected  in  this  station  by  water  flow  grounders,  choke  coils 
placed  in  layers,  and  a  series  of  horn  lightning  arresters;  there  are  also  used  in  con- 
nection with  these  several  oil  resistances.  In  addition  to  this,  the  line  on  both  sides 
is  protected  by  horn  lightning  arresters  with  exceptionally  large  gaps. 


TYPICAL    HYDROELECTRIC    PLANTS. 


393 


From  the  power  plant  at  Hafslund,  lead  four  circuits  of  5000  volts  into  the  sub- 
station. From  here,  the  power  from  Kykkelsrud  and  Hafslund  may  be  distributed 
separately,  or,  as  in  common  practice,  in  parallel.  The  early  equipment  of  the  plants 
and  transmission  system  was  furnished  by  the  Schuckert  Company,  Nuremburg, 
and  the  later  equipment,  by  the  Siemens-Schuckert  Werke,  Berlin. 

HYDROELECTRIC    PLANT,    URFTTALSPERRE,    GERMANY.1 

Forced  to  husband  natural  resources,  particularly  coal,  advantage  has  been 
taken  of  all  kinds  of  water  resources.  The  continent  of  Europe,  for  a  number  of 
years,  has  harnessed  the  yearly  supply  of  the  drainage  area  of  low  mountainous  or 
hilly  countries. 


FIG.  i. — Urfttalsperre  Dam,  showing  Valve  Chamber  Shafts  and  Spillway. 


In  order  to  provide  for  a  steady  water  supply  for  the  whole  year,  more  particularly 
for  the  dry  season,  large  dams  have  been  built  across  valleys.  Having  once  stored 
such  large  bodies  of  water,  the  generation  of  electricity  and  the  transmission  by  high- 
tension  lines  is  the  next  step.  Such  water  resources  are  usually  located  away  from 
centers  of  industry,  and  it  is  but  natural  that  advantage  will  be  taken  of  modern 

1  Reprint  of  author's  article,  "  The  Urfttal  Hydro-electric  Development  in  Germany,"  The  Engineering 
Record,  Sept.  19,  1908.  Based  on  Data  submitted  by  the  Designing  and  Constructing  Engineers. 


394 


HYDROELECTRIC    DEVELOPMENTS    AND    ENGINEERING. 


high-tension  distribution.    The  following  is  a  brief  description  of  the  most  prominent 
one  of  this  kind  in  Europe. 

It  has  a  storage  capacity  of  sixteen  hundred  million  cubic  feet  and  a  transmission 
system  of  35,000  volts.  This  plant  is  known  as  the  "Urfttalsperre,"  l  and  is  situated 
on  the  river  Urft  in  the  Eifel  Mountains,  Germany.  The  capital  of  $2,000,000  was 
subscribed  by  seven  cities  and  districts,  four  of  which  supplied  one-fifth  each;  the 
remaining  fifth  was  supplied  by  the  other  towns.  The  former  are  entitled  to  draw 
power,  and  the  other  three  are  not. 

The  plant  is  capable  of  developing  twenty-two  million  K.W.  hours  per  year,  of 

which  sixteen  million  has  already  been  contracted,  giving  a  yearly  income  of  $165,000. 

Dam.   About  2.5  miles  above  the  junction  of  the  Urft  and  Rur,  is  located  a  dam, 

establishing  a  drainage  area  of  145  square  miles.     This  dam  is  190  feet  high,  having 

a  width  at  the  bottom  of  165  feet,  and 
at  the  top,  17  feet.  The  dam  was  built 
in  arch  form,  with  a  radius  of  650 
feet,  giving  the  crown  a  total  length 
of  about  1000  feet,  about  300  feet  of 
which  is  used  for  spillway,  the  water 
flowing  over  in  cascade. 

The  dam  itself  is  made  up  of  cyclo- 
pean  masonry,  the  largest  of  the  stones 
being  of  a  size  which  required  to  be 
handled  by  two  men.  Both  sides  of  the 
dam  are  faced  with  rough-faced  cut 
stone.  The  dam  was  built  in  one  con- 
tinuous mass,  for  which  purpose,  three 
timber  towers  were  erected  for  elevating 
the  material.  From  these  towers,  tracks 
ran  across  the  dam,  and  by  means  of 
turntables  the  cars  were  placed  on  longitudinal  tracks.  The  mortar  is  composed  of 
lime,  sand  and  trass.  Cement  was  not  used,  because  it  was  feared  the  cement 
would  harden  too  quickly  and  unequally  throughout  the  mass,  thus  producing 
unequal  stresses.  Trass  has  of  late  years  been  much  used  in  German  dam  con- 
struction, as  it  forms,  when  mixed  with  lime  and  sand,  a  hard  and  impervious 
substance  which  dries  slowly  and  equally. 

The  cross  section  of  the  dam  will  be  seen  in  Fig.  2.  For  the  purpose  of  draining 
the  storage  basin,  two  discharge  pipes  are  led  through  tunnels,  through  the  bottom 
of  the  dam.  The  gates  are  located  on  the  upstream  side  in  valve  chambers 
at  the  bottom  of  a  shaft  extending  above  the  high-water  level.  The  tops  of  the 
shafts  and  crown  of  dam  are  connected  by  bridges  to  facilitate  the  operation  of  the 
gates. 

The  upstream  side  of  the  dam  is  plastered  with  "Siderosthen,"  a  waterproof 
material,  then  faced  with  tile.  To  drain  off  the  seepage,  the  dam  is  provided  with 
vertical  seepage  drains. 


FIG.  2. — Section  through  Dam  and  Valve 
Chamber,  Urfttalsperre  Plant,  Germany. 


TYPICAL    HYDROELECTRIC    PLANTS. 


395 


Headrace.  The  power 
plant  itself  is  located  at 
Heimbach  on  the  Rur,  1.7 
miles  away  from  the  dam, 
so  that  at  low  water  it  has  a 
head  of  230  feet,  and  at  high 
water,  360  feet.  A  tunnel 
8850  feet  long,  having  an 
area  of  60  square  feet,  is  cut 
through  the  mountains,  thus 
connecting  the  collecting 
basin  with  the  penstocks. 

On  the  basin  side  of  the 
tunnel  is  located  a  sluice 
gate  operated  through  a 
vertical  shaft  about  150  feet 
high.  On  the  other  side  of 
the  mountain,  at  the  junc- 
tion of  penstock  and  tunnel, 
is  located  an  equalizing 
shaft  which  has  on  the  top 
a  reservoir  that  absorbs  all 
fluctuations  in  the  water 
flow.  This  chamber  per- 
forms the  same  duty  as  a 
standpipe  on  a  penstock, 
but  in  this  case  no  water  is 
wasted.  From  this  shaft 
are  also  operated  the  sluice 
gates  controlling  the  water 
supply  in  each  of  two  pen- 
stocks. The  velocity  of  the 
water  in  the  tunnel  is  six 
and  a  half  feet  per  second. 

From  the  bottom  of  the 
equalizer  shaft,  run  horizon- 
tally two  penstocks  parallel 
to  the  slope  of  the  mountain, 
from  whence  they  run  to  the 
power  house.  The  upper 
portions  of  the  penstocks 
run  through  tunnels  and 
are  partly  embedded  in  con- 
crete, and  covered  with  rilling  to  protect  the  penstock  from  loose  boulders. 


c 

rt 
S 

OJ 

O 

.rf 

I 
| 

ffi 


PL, 


u 

<u 
CO 


5 
c 
o 


PO 

o 


396 


HYDROELECTRIC    DEVELOPMENTS    AND   ENGINEERING. 


Power  House.  The  power  house  consists  of  the  generating  room,  switching  and 
transformer  room;  on  each  side  of  the  switching  room  are  two  wing  towers  for  offices, 
repair  shops,  etc.  As  will  be  seen  from  the  accompanying  illustrations,  the  interior 


FIG.  4. — Cross  Section  and  End  View  of  the  Urfttalsperre  Plant  at  Heimbach,  Germany. 

and  exterior  are  of  the  most  artistic  and  modern  design.  The  generating  room  is 
95  feet  long  by  75  feet  wide;  the  switching  room  is  75  feet  long  and  30  feet  wide. 
The  substructure  up  to  the  floor  line  of  the  generating  room  is  of  concrete,  while  the 
walls  are  of  brick  covered  with  stucco.  The  roof  trusses  are  of  structural  steel  and 
placed  in  pairs;  the  top  and  bottom  chords  are  curved. 


TYPICAL    HYDROELECTRIC    PLANTS. 


397 


The  roof  itself  is  of  Schwemmstein  (special  brick  of  volcanic  origin)  covered  with 
wood  cement  (cement  mixed  with  rough  sawdust). 

The  turbines  are  arranged  in  two  parallel  rows,  the  generators  facing  each  other. 
The  ultimate  equipment  will  consist  of  eight  units,  but  at  present  there  are  only  six 
installed  and  two  exciters.  The  penstocks  before  entering  the  power  house  are 
provided  with  hydraulically  operated  butterfly  valves,  and  the  branches  to  the  tur- 
bines with  hydraulically  operated  gate  valves.  At  the  end  of  the  penstocks  are 
manholes,  and  provision  is  made  for  drainage. 

Turbines  and  Generators.  The  turbines  are  of  the  double-flow  horizontal  Francis 
type,  as  manufactured  by  Escher  Wyss  &  Co.,  Zurich.  They  are  designed  to 
develop  for  minimum  head  of  230  feet,  1550  HP.,  and  for  a  maximum  head  of  360 
feet,  2000  HP.  at  500  R.P.M.  The  casing  is  of  cast  iron;  the  water  is  fed  in  from 
the  circumference  and  discharges  through  two  draft  tubes  which  eventually  unite. 
Since  there  are  two  draft  tubes,  the  runner  is  provided  with  a  right  and  left  hand  set 


FIG.  5. — Main  and  Exciter  Units,  Urfttalsperre  Plant,  Germany. 

of  buckets.  The  single  gate-ring  is  connected  to  two  hydraulic  governors,  auto- 
matically operated.  In  case  of  a  sudden  rise  of  pressure,  a  portion  of  the  water  is 
by-passed  by  the  governor  into  the  tailrace  until  normal  pressure  is  established. 

The  bearings  are  oil  and  water  cooled,  the  water  being  taken  from  the  penstock. 
One  of  the  bearings  is  a  thrust  bearing.  Each  turbine  is  provided  with  a  tachometer, 
manometer  and  two  vacuum  meters,  also  two  cocks,  one  for  releasing  air,  the  other 
for  drainage. 

There  are  two  exciter  turbines  of  200  HP.  each,  running  900  R.P.M.  They  are 
of  the  same  type  and  manufacture  as  the  above  described,  and  are  automatically  and 
hand  controlled,  similarly  to  the  main  turbines.  The  turbines  are  connected  to  the 
generators  by  Zodel  insulated  flexible  couplings. 

The  main  generators,  of  Siemens-Schuckert  Werke,  Berlin,  are  designed  for 
1370  K.W.,  3-phase,  50  cycles,  5000  volts,  and  power  factor  of  0.85.  The  exciters 
are  I35-K.W.,  225-volt  capacity.  In  testing  the  units  for  maximum  capacity  by 
suddenly  throwing  on  or  off  200  K.W.,  the  speed  variation  was  observed  to  be 
2.5  per  cent. 


HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 


FIG.  6. — Cross  Section  of  Turbine,  Urfttalsperre  Plant,  Heimbach,  Germany. 


FIG.  7. — Switchboard,  Urfttalsperre  Plant,  Heimbach,  Germany. 


TYPICAL    HYDROELECTRIC    PLANTS. 


399 


Switching  Room.  The  generator  voltage  is  stepped  up  to  34,000  volts  through 
its  own  transformer,  there  being  no  5ooo-volt  bus-bar  system.  The  secondary  leads 
of  the  transformers  are  connected  in  ring  system  (practically  not  used  in  the  United 
States).  Between  all  junctions  of  the  transformers  and  outgoing  feeders  are  located 
sectionalizing  switches.  Transformer  and  outgoing  feeders  are  provided  with  auto- 
matic oil  switches.  Upon  first  glance  at  the  illustration,1  it  is  seen  that  the  ring 
system  affords  a  complete  protection  against  line  surges;  this  is  obtained  at  the 
sacrifice  of  flexibility  of  operation;  thus  when  one  transformer  is  dead,  the  generator 


FIG.  8. — Transformers  and  Water  Flow  Grounder  (at  the  Left),  Urfttalsperre  Plant,  Germany. 

is  idle.  This  system  is  used  principally  as  a  protection  for  the  transformer.  Between 
generators  and  transformers  are  fuses,  while  between  transformers  and  the  ring 
system  are  remote  control  automatic  oil  switches. 

The  outgoing  feeders,  of  which  there  are  five,  are  protected  by  the  same  type  of 
oil  switches  and  three-pole  sectionalizing  switches.  Between  the  sectionalizing  and 
oil  switches  are  choke  coils  and  connections  to  lightning  arresters  which  are  of  the 
Siemens-Schuckert  horn  type. 

For  further  protection,  there  are  water  rheostats  and  continuous  flow  grounders 
connected  to  the  ring  system,  thus  providing  a  good  ground  connection.  About 

1   (See  Chapter  on  Bus  Bars.) 


400 


HYDROELECTRIC  DEVELOPMENTS  AND  ENGINEERING. 


one-tenth  of  an  ampere  escapes  continuously  through  this  grounded  connection. 
Small  and  gradually  rising  overloads  are  readily  grounded  by  this  device.  The  water 
stream  is  20  inches  long  and  has  a  cross  section  of  two  square  centimeters. 

At  one  end,  about  n  feet  above  the  floor  of  the  generating  room,  the  switchboard 
is  mounted  on  a  mezzanine  floor,  from  which  the  whole  plant  is  controlled.  The 
switchboard  is  of  artistic  design,  consisting  of  three  central  panels  and  four  wing 


FIG.  9. — 35,ooo-volt  Bus  Bar  and  Oil  Switch  Room.     Urfttalsperre  Plant,  Germany. 

panels  on  either  side.  The  framework  is  of  structural  steel,  and  the  panels  of  white 
marble.  Each  of  the  wing  panels  contains  the  necessary  instruments  for  controlling 
one  generator.  The  three  central  panels  contain  the  totalizing  meters  and  master 
control  switches. 

The  transformers,  of  which  there  are  at  present  six,  are  located  in  the  switching 
room  on  the  same  floor  level  as  the  generators;  the  ultimate  capacity  is  eight.  The 
transformers  are  of  the  three-phase  type,  and  are  arranged  in  a  single  row  in  front  of 


TYPICAL    HYDROELECTRIC    PLANTS.  401 

which  is  a  track  pit.  so  that  they  can  be  readily  removed  when  necessary.  Above 
the  transformer  room  is  the  3 5,000- volt  oil  switching  room.  The  switches  are 
arranged  in  two  rows;  they  are  of  the  remote  motor  control  type.  On  the  top  floor 
are  located  the  lightning  arresters  and  outgoing  feeders. 

Transmission  Line.  The  plant  is  provided  for  five  outgoing  feeders;  at  present 
only  four  are  installed.  The  longest  line  is  38.5  miles;  the  others  are  24,  16  and  21 
miles.  The  three  former  have  a  cross  section  of  50  square  mm.;  the  latter,  20  square 
mm.  At  present,  ten  miles  of  the  latter  are  operated  at  only  5000  volts,  although 
designed  for  35,000  volts. 

The  poles  for  the  transmission  line  are  built  up  of  structural  steel,  either  of  two 
channels  and  lattice  work  construction,  or  angle  iron  and  lattice  work,  and  are  set 
in  concrete  blocks. 


FIG.  10. — Protecting  Devices  for  Outgoing  Feeders,  Urfttalsperre  Plant,  Germany. 

They  are  designed  to  carry  high  tension  (35,000)  or  low  tension  (5000)  alone 
or  both  together.  The  high-tension  lines  are  31.5  inches  apart  on  a  leg  and  16  inches 
away  from  the  iron  pole.  •  The  lines  are  carried  on  triple  petticoat  insulators  mounted 
on  steel  pins  fastened  to  wooden  vertical  or  horizontal  cross-arms. 

In  most  cases,  the  lines  skirt  the  towns  and  cities,  and  run  along  the  main  high- 
ways wherever  possible.  Inasmuch  as  these  lines  have  to  cross  many  streets,  railways, 
telephone  and  telegraph  lines,  great  precaution  had  to  be  exercised. 

In  many  cases,  the  public  service  commission  demanded  that  the  guard  wires  be 
carried  on  separate  structures  or  poles. 

Substations.  There  are  two  kinds  of  substations  known  as  "A"  and  "B." 
Substations  "A"  step  down  the  line  voltage  (35,000)  to  5000,  the  other,  "B,"  from 
5000  to  225. 

Substations  "A,"  of  which  there  are  sixteen,  are  of  two-story  masonry  construction. 
The  feeders  go  in  and  out  the  top  story,  where  all  the  high-tension  switching  and 
testing  apparatus  are  located. 


402 


HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 


The  lower  floor  contains  the  low-tension  apparatus  and  transformers.  Each 
station  is  designed  to  accommodate  two  loo-K.W.  transformers,  and  is  built  on  a 
standard  system.  The  station  is  well  provided  with  switches  and  safety  devices,  so 
that  if  a  switch  or  transformer  is  out  of  commission,  the  service  is  not  necessarily 


FIG.  ii. — Type  of  Transmission  House  in  Front  Tower  with  Section  Switch. 

interrupted.  In  connection  with  some  of  the  "A"  stations,  living  houses  are  pro- 
vided, so  that  if  the  patrolman  is  out  on  his  beat,  any  telephone  communication  from 
the  power  house  or  other  substations  may  be  received  by  attendants. 

The  5ooo-volt  lines,  for  the  greater  part,  are  carried  on  wooden  poles,  set  in 
concrete  blocks.     In  some  sections,  where  it  was  not  advisable  to  carry  the  5000- volt 


TYPICAL    HYDROELECTRIC    PLANTS.  403 

lines  overhead  to  the  stations,  they  are  run  underground.  Where  the  lines  go  under- 
ground, they  go  down  a  lattice-girder  steel  pole  provided  with  lightning  arresters 
and  choke  coils. 

The  "B"  or  low-tension  substations  are  for  the  most  part  built  on  a  standard 
system,  except  in  some  cases,  where  the  consumer  builds  his  own  substation. 

It  might  be  of  interest  to  state  that  the  German  government  investigated  the 
effect  the  3 5,000- volt  alternating  current  transmission  line  has  on  its  long-distance 
tebphone  system. 

There  was  a  certain  telephone  trunk  line,  much  influenced  by  the  high-tension 
alternating  current.  The  investigation  l  proved  that  the  transmission  line,  2600  feet 
away  from  the  telephone  line,  still  affected  that  particular  trunk  line,  while  other 
lines  closer  tc  same  were  unaffected. 

Financial  Aspects.  The  complete  hydroelectric  transmission  system,  including 
high  and  low  tension  lines,  cost  approximately  $2,500,000,  of  which,  the  dam  cost 
$1,000,000.  The  latter  item  is  small  in  comparison  with  similar  plants.  Dams  of 
this  character,  although  primarily  built  for  water  power  developments,  serve  also  to 
prevent  floods  in  certain  seasons.  Comparing  the  cost  of  same  per  cubic  foot  of 
v/ater  impended,  with  dams  of  similar  plants,  the  following  figures  are  submitted. 

Urfttal,  0.06  cent;  Remscheid,  0.38  cent;  Barmen,  0.57  cent;  Nonsdorf,  1.21  cents, 
which  gives  an  average  cost  of  0.55  cent  per  cubic  foot  of  water  impended. 

When  a  consumer  is  supplied  with  current  for  power  from  the  5000- volt  line  directly 
0.9  to  i.o  cent  is  charged  per  K.W.  hour,  provided  he  furnishes  his  own  transformer 
equipment,  otherwise  the  charge  is  1.5  to  6  cents  per  K.W.  hour,  depending  on  the 
amount  of  power  consumed.  If  current  is  supplied  from  the  225-volt  distribution 
system,  the  price  varies,  with  a  maximum  of  8.5  cents.  When  the  consumer  guarantees 
a  certain  amount  of  yearly  power,  there  is  a  rebate  of  30  per  cent. 

All  current  for  light,  irrespective  of  the  amount,  drawn  from  225-volt  circuit,  is 
supplied  at  10  cents  per  K.W.  hour  for  the  first  5000  K.W.  hours;  above  this  8  cents  is 
charged;  and  when  drawn  from  the  5000- volt  circuit,  there  is  a  rebate  of  20  per  cent. 

Although  the  plant  has  not  yet  reached  its  full  capacity,  the  returns  on  the  money 
invested  already  amount  to  4  per  cent. 

UPPENBORN   PLANT  AND   ITS   50,000-VOLT  TRANSMISSION   SYSTEM,  MUNICH, 

GERMANY.2 

To  supply  the  city  of  Munich  with  additional  electrical  energy,  and  to  run  in 
parallel  with  the  several  existing  municipal  steam  and  hydraulic  plants,  a  new 
municipal  hydroelectric  plant  has  recently  been  completed. 

It  utilizes  the  water  of  the  river  Isar  in  Moosburg,  where  three  i88y-H.P.,  double 
twin  turbines  are  installed.  Energy  is  generated  at  5000  volts,  but  the  E.M.F.  is 

1  Die  Hochspannungs-Kraftiibertragung  an  der  Urfttalsperre,  by  O.  Brauns.      Elektrotechnische  Zeit- 
schrijt,  April  9,  1908. 

2  "  Das  Uppenbornkraftwerk,"  by  S.  Meyer,  H.  Niesz  and  K.  Dantscher.      "  Electrische  Kraftbetriche 
und  Bahnen,"  Nos.  16,  17,  18,  19  and  20,  1908.      See  also  "Electrical  World  "  Nov.  28,  1908.      "  German 
50,000  Volt  Transmission  System." 


404 


HYDROELECTRIC  DEVELOPMENTS  AND  ENGINEERING. 


increased  to  50,000  volts  for  transmission  over  two  parallel  circuits  to  the 
substation  near  the  city  of  Munich,  where  the  E.M.F.  is  decreased  to  5000  volts 
for  distribution. 

This  plant,  known  as  the  Uppenborn  station,  being  the  latest  of  German  hydro- 
electric undertakings,  possesses  many  novel  features,  particularly  on  the  electrical  end. 

Thirty-three  miles  below  the  city  of  Munich  the  river  Isar  makes  a  bend,  which 
is  cut  off  by  a  head  and  tail  race  canal  about  2.5  miles  in  length,  having  a  net  fall  of 
28.1  feet  at  low  water  and  24.8  feet  at  high  water.  Permission  was  given  to  draw 
2500  cubic  feet  of  water  per  second  during  207  days,  while  during  the  remainder, 
including  the  dry  season,  only  1070  cubic  feet  is  available. 

Headrace.  Just  below  the  junction  of  the  headrace  and  the  river,  a  dam  was 
thrown  across  the  river  at  about  right  angles.  For  this  purpose  the  width  of  the  Isar 
was  increased  from  225  feet  to  619  feet.  On  the  opposite  end  from  the  intake  is  a 


FIG.  i. — Power  House,  Uppenborn,  Germany. 


spillway  328  feet  long.  Adjoining  the  spillway  is  a  fish  passage  6.5  feet  wide,  built 
up  in  steps.  Next  to  this  are  the  sluice  gates  for  regulating  the  head.  They  are 
divided  into  four  sections,  each  55.7  feet  wide,  three  of  which  are  separated  by  con- 
crete pilasters,  while  the  fourth  is  separated  by  a  lock  26.25  ^eet  wide  for  passing 
boats,  etc.  This  lock,  having  two  mechanically  operating  swinging  gates  on  the 
upstream  end,  is  about  150  feet  long.  The  bottom  has  a  slope  of  about  2  per  cent. 
It  is  made  of  concrete  faced  with  planking. 

The  sluice  gate  passages  adjoining  the  lock  are  subdivided  into  two  sections  by  a 
removable  guide,  for  the  purpose  of  giving  free  passage  for  floating  debris,  etc.  The 
two  passages  near  the  intake  are  divided  into  three  sections,  and  the  guides  here,  for 
the  sluice  gates,  are  stationary. 

Each  sluice  gate  is  divided  into  two  sections,  one  upper  and  one  lower.  They 
are,  however,  not  of  the  same  size,  the  lower  being  the  smaller,  thus  enabling  the 
sections,  due  to  the  hydrostatic  head,  to  be  operated  by  the  same  amount  of  power. 


TYPICAL    HYDROELECTRIC    PLANTS. 


405 


a 

o 

o 


Two  such  sections,  or  one  gate,  can  be  lifted  by  a  3-phase,  lo-HP.  motor  in  ten 
minutes.  When  operated  by  a  hand  windlass  with  a  ratio  of  i :  2800,  50  minutes  are 
required  to  lift  one  section.  On  the 
down-stream  side  of  the  gates  resting 
on  the  concrete  piers,  is  an  operating 
gallery  of  structural  steel. 

The  bottom  of  the  intake  to  the 
headrace  is  about  7  feet  above  the  bed 
of  the  river,  thus  preventing  foreign 
material,  such  as  gravel  and  sand, 
from  entering  the  headrace.  As  the 
provision  cuts  down  the  depth  of  the 
water  to  4.9  feet,  the  width  of  the 
intake  was  made  125  feet,  thus  giving 
a  velocity  of  3.9  feet  with  a  friction  or 
head  of  loss  of  4  inches. 

This  intake  passage  is  divided  by 
a  massive  concrete  pier,  and  in  order 
to  further  reduce  the  size  of  the  sluice 
gates  they  are  subdivided  into  four 
sections  by  structural  steel  sluice 
guides.  Each  gate  is  divided  in  two 
parts  and  operated  in  the  same 
manner  as  those  described  above. 

At  the  side  of  the  dam  and  intake 
is  an  attendant's  house,  which  con- 
tains a  transformer  for  supplying 
energy  to  gate  motors.  On  the  other 
side  of  the  intake  is  a  lock,  similar  to 
the  one  mentioned,  for  passing  boats 
into  the  headrace. 

The  headrace  canal  is  1.3  miles 
long,  and  is  built  with  a  slope  of  i  in 
3000  for  a  calculated  velocity  of  4  feet 
per  second.  It  is  54.5  feet  wide 
on  the  bottom,  with  sideslopes  of  i 
to  1.5.  Under  ordinary  conditions 
the  depth  of  the  water  is  9.2  feet. 
Throughout  the  greater  part,  the  sides 
of  the  canal  are  finished  off  in  embank- 
ments, which,  at  the  highest  point, 
are  16.5  feet  above  the  natural  ground. 

At  a  low  point  the  headrace  crosses  a  creek  which  is  passed  underneath  through 
two  culverts. 


u 


C 

-3 
3 
5b 

3 


406 


HYDROELECTRIC  DEVELOPMENTS  AND  ENGINEERING. 


Generating  Plant.  The  power  house  lies  across  and  at  right  angles  to  the  head- 
race, which  is  here  175  feet  wide.  At  one  end  of  the  power  house  is  a  lock  for  passing 
boats  and  a  fish  way,  similar  to  those  at  the  dam.  At  the  other  end  is  a  sluice  gate 
and  passage  for  letting  off  the  headrace  water  into  the  tailrace;  the  latter  is  i.i  miles 
long.  Some  difficulty  was  encountered  during  the  excavating,  because  part  of  the 
work  runs  through  marshy  land. 

The  generating  and  switching  rooms  are  housed  under  a  common  roof.  The 
former  is  103.3  ^eet  l°nS  anc^  2^  ^eet  Wl^e-  ^n  order  to  give  the  generating  room  a 
pleasing  appearance,  a  ferro-arched  ceiling  is  built  up  under  the  roof  truss,  38  feet 
above  the  floor  level.  The  whole  room  is  kept  in  light  color,  and  well  illuminated. 
The  floor  and  wainscoting  are  tiled. 


FIG.  3. — Interior  of  Generator  Room,  Uppenborn  Plant,  Germany. 

At  an  angle  of  72  degrees  to  the  flow  of  the  water  to  the  turbine  chamber,  and  in 
front  of  the  sluice  gates,  are  racks  built  up  of  2.25  by  o.25~inch  bars,  spaced  with  a 
clearance  of  one  inch.  The  sluice  gate  for  each  turbine  is  11.5  feet  high  and  24  feet 
wide,  and  is  divided  vertically  into  three  sections,  which  can  be  interconnected  for 
motor  operation. 

The  sluice  gate  seen  foremost  in  Fig.  i  is  14.8  feet  high  and  13.1  feet  wide,  and 
its  purpose  is  for  emptying  the  headrace  as  above  indicated.  On  the  other  end  of 
the  sluice  gates  is  the  gate  for  the  lock;  it  is  26.25  feet  wide  and  16  feet  high,  and  is 
lowered  when  the  water  is  let  off.  All  sluice  gates,  with  the  exception  of  the  latter, 
can  be  motor  operated.  On  the  downstream  side  of  the  gates  is  a  gallery  from 
which  they  are  operated  by  hand. 

Turbines  and  Generators.   The  turbine  chambers  are  located  between  the  gates 


TYPICAL    HYDROELECTRIC    PLANTS. 

UNIV..OF  CAU 

reinforced 


and  the  generating  room,  the  roof  being  flush  with  the  street  and  made  of 


concrete.  There  are  installed  three  twin  inward-flow  Voith  turbines,  mounted  on  a 
horizontal  shaft,  each  having  an  output,  with  a  water  consumption  of  785  cubic  feet 
and  a  head  of  26  feet,  1887  HP.  at  150  R.P.M.  Each  twin  turbine  has  its  own  draft 
tube;  the  two  of  a  complete  unit  join  into  a  single  draft  tube,  which  is  part  of  the 
foundation,  and  discharge  into  the  tailrace. 

During  the  greater  part  of  the  year  there  is  surplus  water,  to  utilize  which,  a  224-HP. 
twin  turbine,  consuming  100  cubic  feet  of  water  per  second,  making  300  R.P.M.,  has 
been  installed.  The  generator  of  this  turbine  is  a  three-phase,  5ooo-volt,  5o-cycle 
machine,  designed  for  an  output  of  210  K.W.  at  a  power  factor  of  0.9.  To  the  unit 
there  is  coupled  a  no- volt  exciter.  The  operation  of  this  set  is  kept  independent 
from  the  remainder  of  the  plant,  as  it  supplies  energy  for  the  city  of  Moosburg. 
However,  provision  is  made  so  that  in  case  of  emergency  it  can  be  joined  in  parallel 
with  the  rest  of  the  plant,  as  will  be  seen  below. 

The  control  of  each  of  the  main  turbine  sets  is  accomplished  by  an  oil-actuated, 
hydraulic  governor,  located  in  the  generating  room.  The  oil  is  supplied  at  295- 
pound  pressure  by  pumps  operated  from  the  turbine  shafts.  The  oil  piping  of  the 
different  pumps  is  interconnected  so  that  one  may  assist  another.  For  synchronizing 
the  generators,  the  governors  are  equipped  with  small  motors,  controlled  from  the 
main  switchboard. 

The  turbine  shafts  are  rigidly  coupled  to  those  of  the  three-phase  alternators, 
which  are  of  the  revolving-field,  5ooo-volt,  5o-cycle  type.  With  unity  power  factor 
the  output  of  each  generator  is  1400  K.W.  Overhanging  on  each  shaft  is  mounted 
a  I7-5-K.W.,  no-volt  exciter. 

To  accommodate  the  type  of  turbine  generator  installed,  the  floor  had  to  be 
placed  about  21  feet  below  the  ground  level,  which  is  about  3.5  feet  above  the  high- 
water  level  in  the  tailrace,  thus  placing  the  bottom  of  the  generator  pit  some  6  feet 
beneath  the  high-water  level.  To  prevent  seepage  from  entering  the  generator  pits, 
and  also  the  trenches  for  the  generator  leads  to  the  switchboard,  they  are  lined  with 
steel  plates.  For  the  same  reason,  the  generator  leads  are  taken  off  from  the  upper 
part  of  the  armature  and  passed  through  a  column  to  the  trenches  leading  to  the 
switchboard. 

Switch  Gear.  The  three  main  generators  feed  energy  into  one  bus-bar  system, 
connected  at  each  end  to  transformers.  Between  the  junctions  are  sectionalizing 
switches,  thus  keeping  the  two  outgoing  lines  to  Munich  entirely  separate.  All 
switching  is  done  on  the  5ooo-volt  side,  there  being  no  high-tension  bus-bars. 

For  each  outgoing  line  there  is  one  three-phase  transformer  of  2ooo-K.V.A. 
rating  for  increasing  the  E.M.F.  from  5000  to  50,000  volts.  They  are  of  the  Siemens- 
Schuckert,  oil-insulated,  water-circulated  type.  By  using  60  cubic  feet  of  cooling 
water  per  hour,  with  the  transformers  under  full  load,  the  temperature  of  the  oil 
surface  is  95°  F.  above  that  of  the  incoming  water.  The  efficiency  at  full  load  is 
98  per  cent.  The  ohmic  resistance  drop  is  0.95  per  cent,  while  the  impedance  drop 
at  full  load  current  is  3.5  per  cent. 

The  secondary  windings  of  the  transformers  are  split  up  into  sections  with  the 


408 


HYDROELECTRIC  DEVELOPMENTS  AND  ENGINEERING. 


leads  brought  outside,  so  that  they  can  be  readily  changed  from  star  to  delta  con- 
nection for  giving  a  2 5,000- volt  transformation  if  desired. 

The  transformer  casings  are  made  of  steel  plates,  and  rest  on  rollers  and  tracks, 
whereby  they  can  be  shifted  to  the  generating  room  and  there  handled  by  a  1 6-ton 
overhead  crane  for  repairs.  Each  transformer,  when  filled  with  oil,  weighs  n  tons. 

A  novel  feature  connected  with  the  transformer,  and  of  especial  value  to  hydraulic 
plants,  is  the  utilization  of  the  circulating  water  of  the  transformers  for  heating  the 
various  rooms  of  the  plant. 


FIG.  4. — Wall  Outlet,  5o,ooo-volt  Transmission  System,  Uppenborn,  Germany. 


The  water  for  cooling  the  transformers,  as  well  as  that  for  the  water  flow  grounders 
and  for  drinking  purposes,  is  supplied  by  a  5-HP.  centrifugal  pump,  which  delivers 
to  an  elevated  tank.  The  pump  works  automatically  between  the  limits  of  45  pounds 
and  75  pounds.  Use  is  made  of  a  3-HP.  auxiliary  pump  when  the  cooling  water  of 
the  transformers  is  utilized  for  heating  purposes.  Another  pump  removes  possible 
seepage. 

In  front  of  the  switchboard  is  a  controlling  bench  from  where  the  generator 
room  is  readily  overlooked.  It  contains  all  levers  and  wheels  on  the  flat  surface,  while 
the  instruments  are  mounted  on  the  incline.  From  this  desk,  the  attendant  starts 
the  turbines  by  means  of  the  motors  on  the  sluice  gates.  Moreover  the  field  and 
speed  control,  synchronizing  as  well  as  loading  the  generators,  is  done  from  this 
point  without  the  attendant  losing  sight  of  the  generating  room. 

The  switchboard  is  made  up  of  several  panels,  four  for  generators  and  three  for 
the  outgoing  lines.  All  are  of  the  wagon  panel  type  of  the  Allgemeine  Elektricitats 
Gesellschaft,  consisting  of  a  small  carriage  resting  on  wheels  upon  the  steel  framework 


TYPICAL    HYDROELECTRIC    PLANTS.  409 

of  the  switchboard.  The  advantage  of  the  wagon  panel  system  is  that  the  panel 
with  equipment  can  be  readily  withdrawn  for  inspection  and  repair.  The  electrical 
connections  are  made  by  copper  clips  on  the  back  of  the  carriage,  which  is  done  by 
sliding  in  the  wagon  panel.  Each  generator  panel  contains  an  oil  switch  provided 
with  an  overload  and  reverse  current  time-limit  relay,  which  can  be  operated  by 
hand  wheel  on  the  panel  or  by  a  pilot  switch  on  the  controlling  bench.  The  two 
series  transformers  for  the  relays  and  one  for  the  ammeter  are  also  placed  in  the 
carriage,  while  the  switch  indicators  are  located  on  the  controlling  bench.  There 
is  also  a  small  three-phase  transformer  for  the  synchronism  indicator  and  one 
for  the  wattmeter;  the  instruments  themselves  are  placed  on  the  controlling 
bench. 

The  individual  equipment  of  the  carriages  are  disconnected  by  small  switches 
placed  in  a  row  on  the  switchboard  front.  Each  of  the  transformer  panels  contains 
an  oil-switch  with  an  excess-current  cut-out  and  a  wire  break  relay;  three  series 
transformers;  one  ammeter  and  its  transformer;  one  potential  transformer,  and  two 
dry  elements  for  the  wire  break  relay. 

Lightning  Protection.  In  the  power  house,  as  well  as  the  substations,  there  are 
very  extensive  systems  for  protecting  against  lightning.  The  equipment  in  the 
power  house  is  as  follows:  For  direct  lightning  strokes  there  is  placed  at  each  phase- 
lead  a  horn-gap  of  nine-sixteenths  inch,  connected  to  large  water  rheostats,  located 
in  an  annex  of  the  power  house.  In  the  upper  floor  of  the  switching  rooms  are  four 
choke  coils  connected  in  series,  each  preceded  by  a  horn  gap.  Between  these  and 
the  transformer  is  a  coil  known  as  the  generator  choke  coil,  which  is  also  provided 
with  a  horn  gap.  All  the  gaps  for  each  phase  lead  (2.25-inch  setting)  have  a  common 
ground.  To  the  grounding  device  is  connected  an  oil  rheostat  to  prevent  the  genera- 
tor current  from  following  the  lightning  stroke.  To  take  care  of  light  surges,  water- 
flow  grounders  are  installed. 

To  equalize  the  pressure  between  the  phases,  there  are  three  horn  spark-gaps 
connected  in  "star"  to  the  middle  point  of  the  transformers. 

It  might  be  of  interest  to  state  that  the  waterflow  grounders  are  designed  to  carry 
off  from  o.i  ampere  to  0.15  ampere,  according  to  the  chemical  composition  of  the 
water.  This  means  that  a  three-phase  grounder  leads  off  9  K.W.  and  the  power 
for  four  grounders  amounts  to  36  K.W.,  which  is  less  than  i  per  cent  of  the  power  to 
be  transmitted.  The  water  is  supplied  by  two  centrifugal  pumps.  . 

The  horn-gaps,  of  which  there  are  five  per  phase,  are  spaced  8  inches  apart,  between 
which  are  double  asbestos  partitions  7.8  feet  high.  As  they  are  located  on  the  upper 
floor  of  the  switching  rooms,  the  roof  and  roof-truss  over  the  horn-gap  room  is  lined 
with  cork  plates  covered  with  incombustible  material. 

As  stated,  the  2io-K.V.A.  generator,  supplying  5000  volts  for  the  city  of  Moosburg, 
is,  under  ordinary  conditions,  operated  independently  of  the  rest  of  the  plant  by 
means  of  sectionalizing  switches  in  the  bus-bars.  The  energy  is  conveyed  by  means 
of  a  cable  running  along  the  headrace.  At  the  attendant's  house,  near  the  dam,  a 
tap  is  made  to  feed  a  3O-K.W.,  5000- volt  to  no-volt  transformer  for  operating  the 
sluice  gates. 


4io 


HYDROELECTRIC    DEVELOPMENTS    AND    ENGINEERING. 


Insulators.  All  station  insulators  for  50,000  volts  are  made  up  of  three  corrugated 
cylindrical  porcelain  sections,  held  together  by  a  mechanical  screw  coupling.  The 
height  over  all  is  11.5  inches;  the  diameter  of  the  lower  section  is  5.5  inches,  and  that 
of  the  remainder,  3.75  inches.  The  design  is  such  that  the  total  porcelain  thickness 
between  the  metal  couplings  is  2.25  inches,  while  the  surface  leakage  path  is  23  inches. 
The  corrugations  have  the  effect  of  making  the  high  pressure  noticeable  by  loud, 
hissing,  dark  discharges,  without  measurable  loss.  These  insulators  are  placed  at 
least  20  inches  apart,  while  those  carrying  ground  connections  are  spaced  not  less 
than  12  inches  apart. 

The  high-tension  wall  outlets  on  the  main  as  well  as  on  the  substations  are  of  the 
design  seen  in  Fig.  4.  An  outlet  consists  of  two  concentric  corrugated  porcelain 


FIG.  5. — Type  of  Insulators.     Uppenborn  Transmission  System,  Germany. 

bushings  cemented  together,  which  in  turn  are  cemented  in  the  bell-shaped  end  of 
a  tile  cylinder  16  inches  in  diameter.  As  the  radius  of  the  line  conductor  is  only 
3.5  mm.,  it  was  thought  advisable  to  increase  its  diameter  artificially  by  placing  a 
brass  tube  85  mm.  (3!  inches),  around  the  conductor,  thus  cutting  down  any  arcing 
effects  due  to  brush  discharges.  Although  the  distance  between  line  and  ground 
is  reduced,  the  arcing  effects  are  no  more  noticeable. 

Transmission  System.  The  transmission  system  is  32  miles  long,  and  calculated 
to  transmit  4000  K.W.  at  50,000  volts,  for  which  purpose  two  separate  transmission 
lines  were  installed.  The  conductors  consist  of  a  seven-strand  cable,  16  square  mm. 
in  cross  section,  and  spaced  4.6  feet  on  a  leg.  Under  normal  operation  both  circuits 
are  alive,  and  under  this  condition  the  total  resistance  drop  is  about  uoo  volts,  and 
the  reactance  drop  430  volts.  The  power  factor  at  the  power  house  is  0.95,  while  at 
the  substation  it  is  unity.  This  difference  is  due  to  the  charging  current. 


TYPICAL    HYDROELECTRIC    PLANTS. 


411 


FIG.  6. — Transformer  and  Lightning  Arrester  Station  Hirschau,  Uppenborn  Transmission 

System,  Germany. 


FIG.  7. — Sub  Station  Hirschau  and  Lightning  Arrester  House,  Uppenborn  System,  Germany. 


412 


HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 


As  will  be  seen  in  Fig.  5,  there  are  two  different  kinds  and  manufacture  of  line 
insulators;  both  are  of  the  three-petticoat,  two-piece  type,  glazed  together  in  the 
manufacture.  The  insulator  shown  at  the  right  hand  is  9  inches  high,  the  head 
being  8.75  inches  in  diameter.  The  other  is  10.25  inches  high,  the  head  being 
9.5  inches  in  diameter. 

Before  the  contracts  for  the  transmission  structures  were  let,  tests  were  con- 
ducted on  (i)  wooden  A-frame  structure;  (2)  steel  tube  poles;  (3)  Mannesmann 
tube  poles;  (4)  latticed  tower  of  angle  iron;  (5)  I-beam  A-frame. 

The  following  table  gives  a  comparison  of  the  tests  on  the  above  structures, 
together  with  the  price  in  marks.  The  structures  are  tabulated  successively,  as 
above  numbered;  the  data  are  expressed  in  the  metric  system  and  serve  for  ready 
comDarison. 


i 

2 

3 

4 

5 

Safe  load  in  kilograms    

IOO 

I8OO 

22OO 

870 

1800 

Cost    including  two  arms,  in  marks  

?e.  20 

4O.  7? 

4<;.  20 

80    7O 

dO    OO 

It  will  be  noticed  that  the  wooden  structure  was  not  favorable,  especially  as  the 
line  passes  through  marshes,  and  the  life  of  a  wooden  structure  is  short.  The 
I-beam  structure  outstripped  the  others  regarding  safe  load  and  price,  which  is  the 
reason  why  these  poles  were  adopted. 

The  standard  poles  are  23  feet  high  to  the  lower  insulators.  The  standard  spac- 
ing is  about  165  feet.  The  two  parallel  poles  are  spaced  about  13  feet  apart;  they 
are  embedded  in  concrete  blocks  about  5  feet  deep.  Each  pole  is  made  up  of 
two  5. 5-inch  I-beams;  for  present  conductors,  3. 5-inch  I-beams  would  have  suf- 
ficed, but  as  in  the  future  new  plants  will  be  added  heavier  line  conductors  were 
employed. 

There  is  a  total  of  2260  towers,  which  were  erected  by  two  gangs,  each  consisting 
of  40  men  capable  of  erecting,  on  the  average,  20  towers  per  day.  As  nearly  the  whole 
course  follows  the  river  Isar,  all  of  the  material  was  convenientl  transported  on 
boats. 

There  are  only  a  few  special  structures  throughout  the  whole  line.  Wherever 
the  transmission  line  crosses  a  telephone  line  higher  poles  are  chosen.  No  guard  or 
net  wiring  is  employed.  In  one  instance  a  special  lattice  girder  construction  was 
erected  for  crossing  the  State  telephone  system.  The  line  crosses  the  Isar  three  times, 
and  at  these  points  special  angle-iron  lattice-constructed  towers  are  made  use  of  to 
carry  spans  of  365  feet.  For  these  spans,  instead  of  copper,  bronze  conductors  of 
29  sq.  mm.  were  used.  The  poles  are  grounded  by  a  1 2-inch  by  1 2-inch  plate;  all 
poles  are  interconnected  electrically  by  an  iron  wire. 

The  whole  line  is  transposed  three  times,  thus  dividing  the  line  into  four  sections, 
to  nullify  the  electrostatic  and  inductive  effect  on  the  telephone  line.  The  last 
transposition  brings  the  phase  leads  into  their  original  position. 


TYPICAL    HYDROELECTRIC    PLANTS. 


413 


FIG.  8. — Lightning  Arrester  Equipment  at  Substation  Hirschau,  Uppenborn  System,  Germany. 


FIG.  9. — Transformer  and  Water  Flow  Grounder,  Substation  Hirschau,  Uppenborn  Trans- 
mission System,  Germany. 


HYDROELECTRIC   DEVELOPMENTS   AND   ENGINEERING. 


Section  House.  Midway  between  the  power  house  and  Munich,  at  Achering,  there 
is  a  lightning-arrester  station,  through  which  the  circuits  pass.  This  station  is 
divided  up  into  two  separate  rooms,  one  for  each  circuit.  Here  are  located  three 
horn-gaps  with  2-inch  setting;  they  are  6  feet  apart,  separated  by  double  asbestos 
partitions.  Each  phase  lead  is  connected  to  a  5ooo-ohm  rheostat  submerged  in  oil 
and  then  grounded  by  plates  connected  to  the  ground  wires  of  the  towers.  Section 
switches  are  placed  between  the  lines  and  horn-gaps,  so  that  the  latter  can  readily 


FIG.  10. — Siemens-Schuckert  Wagon  Panel. 


be  cut  out.  Line  section-switches  are  placed  at  intervals  of  0.6  mile  in  order  to 
facilitate  the  localization  of  faults. 

The  four  sections  are  watched  by  four  patrolmen,  each  covering  twice  daily  eight 
miles.  After  a  quarter  year  of  operation  it  was  found  more  economical  to  replace 
the  four  patrolmen  by  two  men  mounted  on  motor-cycles. 

The  lightning-arrester  station  has  two  telephones,  one  for  each  transmission  line. 
They  are  carried  on  the  towers  of  the  transmission  line  about  3.5  feet  below  the 
lowest  conductor.  The  telephone  lines  are  transposed  every  650  feet  to  counter- 
balance any  inductive  effects. 


TYPICAL    HYDROELECTRIC    PLANTS. 


415 


Substation.  Energy  is  received  at  the  end  of  the  line  at  the  Hirschau  transformer 
station  at  about  48,000  volts,  the  E.M.F.  being  then  transformed  to  5000.  The 
lines  enter  the  substation  with  protection  devices  similar  to  those  at  the  power  house, 
and  feed  into  the  two  three-phase  transformers.  On  the  secondary  side  is  a  5000- 
volt  bus-bar  system,  divided  into  two  sections  by  sectionalizing  switches.  From 
here  three  connections  are  made  to  the  already  existing  distributing  system  in  the 
city  of  Munich. 

The  transformer  station  is  seen  in  Fig.  6.  The  adjacent  small  building  contains 
protecting  apparatus  for  direct  lightning  strokes.  The  architecture  of  the  buildings, 


FIG.  n. — Horn  Gaps  and  Water  Rheostats  in  Lightning  Arrester  House  at  Substation,  Hir- 
schau, Germany. 


particularly  that  of  the  larger  one,  is  that  of  a  south  Bavarian  farmhouse.  It  is  built 
up  of  brick,  to  which  stucco  is  applied.  On  the  ground  floor  it  contains  the  trans- 
formers, 5ooo-volt  switching  apparatus  and  water  flow  grounders.  On  the  second 
floor  are  the  generator  choke  coils,  placed  in  oil;  choke  coils  and  oil  rheostats.  On 
the  upper  floor,  directly  above  the  choke  coils,  are  the  horn-gap  arresters. 

The  transformers  are  of  the  Siemens-Schuckert  type,  similar  to  those  installed 
in  the  power  house.  Each  is  located  in  a  room  separated  by  an  inspection  or  repair 
room.  They  rest  on  rollers  and  tracks  and  can  readily  be  moved. 

The  switchboard  in  the  substation  is  also  of  the  wagon  panel  type  of  Siemens- 
Schuckert  make,  and  differs  from  the  previously  described  one  in  that  the  wagon  is  a 


4i6 


HYDROELECTRIC   DEVELOPMENTS   AND   ENGINEERING. 


whole  panel  running  on  tracks  in  the  floor  of  the  switching  room.  Each  wagon 
contains  an  oil  switch  operated  by  hand,  provided  with  an  overload  relay  and  one 
ammeter  with  its  transformer. 

There  is  a  y-K.W.,  5000/1  lo-volt,  three-phase  transformer  to  supply  energy  for 
the  operation  of  two  centrifugal  pumps,  for  circulating  the  cooling  water  of  the 
transformers,  and  for  water-flow  grounders,  rheostats,  etc.  This  transformer  also 
supplies  energy  to  a  i-K.W.  motor  generator  set,  assisted  by  a  30- volt  battery  of 
81  ampere-hour  rating,  to  light  the  station. 

Telephones.  The  transformer  station  is  connected  to  all  stations  and  substations 
with  which  it  runs  in  parallel  by  private  and  local  telephones  and  with  the  main 
generating  station  in  three  different  ways.  Two  are  the  high-tension  lines  running 
beneath  the  5o,ooo-volt  circuits,  and  the  other  runs  along  the  poles  of  the  long-distance 
state  telephone,  which  is  not  influenced  by  high-tension  lines. 

Special  precaution  is  taken  with  the  high-tension  telephones  to  guard  against  all 
possible  danger.  As  stated,  the  5o,ooo-volt  transmission  lines  are  transposed  twice, 
and  the  telephone  line  every  650  feet.  This  arrangement,  however,  was  not  con- 
sidered perfect.  The  telephone  line  is  carried  on  two-piece,  three-petticoat  insulators 
tested  at  70,000  volts.  The  telephone  is  protected  first  by  small  horn-gap  arresters, 
then  high-pressure  fuses  grounded  with  small  spark  gaps;  next  by  fine  fuses  known 
as  "  Bosepatronen,"  grounded  by  two  carbon  telephone  lightning  arresters.  A 
variable  water  rheostat  is  shunted  in  ahead  of  the  Bosepatronen,  and  by  adjusting 
the  electrodes  the  buzzing  effect  of  electrostatic  induction  is  eliminated,  thus  giving 
good  articulation. 

It  was  thought  unsafe  to  connect  the  line  directly  to  the  transmitter,  therefore 
between  the  latter  and  the  line  is  cut  in  a  microphone-telephone,  which  is  connected 
to  the  transmitter  by  pressed  paper  tubes.  The  receivers  are  connected  to  the 
telephone  by  flexible  tubes. 

Cost.  The  table  below  expressed  in  marks  gives  comparative  figures  of  the 
entire  system,  which  totalizes  approximately  $800,000. 


Items 

Marks. 

Main  dam  .   .     .                ...    

8<;c:,!;2v  06 

Regulating  gates                    .    .      .  •        

138,124.  64 

Headrace  and  turbine  substructure     

1,065,129.04 

86,522.  42 

142,  303.  o? 

6 

Electrical  equipment   

272,046.  57 

7 

Transmission  system   

464,552.02 

8 

i34,<:Qo.  38 

Accessories                   

42,216.  59 

Retention  dams,  fish  rights,  etc  

62,030.  6? 

Supervising  charge             .           

26.320.  23 

Total  

3,290,358.  55 

TYPICAL  HYDROELECTRIC  PLANTS.  417 

THE    BRUSIO    HYDROELECTRIC  PLANT  AND    ITS  50,000-VOLT  SWISS-ITALIAN 

TRANSMISSION    SYSTEM.1 

The  largest  and  most  recent  hydroelectric  installation  in  continental  Europe  is 
that  at  Brusio  in  Campocologna  (Granbiinden),  the  southeastern  corner  of  Switzer- 
land. Some  3155  feet  above  sea  level,  bordered  by  the  slopes  of  the  Bernian  Moun- 
tains, lies  the  lake  of  Poschiavo.  This  lake  receives,  among  others,  the  waters  of 
the  River  Poschiavino  and  its  tributaries  as  well  as  those  of  the  River  Cavagliasco, 
which  in  turn  collects  the  waters  of  the  glaciers  Cambrena  and  Palii.  The  total 
drainage  area  which  feeds  this  lake  is  75  square  miles.  The  area  of  the  lake  is 
0.77  square  mile,  and  the  greatest  depth  is  260  feet. 

Owing  to  the  high  altitude  of  the  lake,  the  water  supply  in  the  winter  time  is 
considerably  less  than  during  other  seasons,  consequently  the  equipment  of  the 
plant  with  proper  regulating  devices  became  very  essential.  Therefore  one  of  the 
foremost  requirements  consisted  in  damming  the  lake  at  its  outlet,  where  the  River 
Poschiavino  continues,  so  that  the  water  level  of  the  lake  may  be  raised  3.3  feet  above 
the  normal,  and  lowered  by  siphoning,  as  much  as  24.3  feet  below  the  normal  level, 
thus  providing  a  natural  reservoir,  giving  a  reserve  water  supply  of  520,000,000  cubic 
feet. 

The  headrace  leading  from  the  lake  is  carried  to  Monte  Scala,  a  distance  of  3.25 
miles,  where  a  collecting  basin  is  provided  by  a  tunnel  through  the  mountain  at  a 
considerable  depth. 

The  power  plant  is  located  at  Campocologna,  receiving  the  water  through  pen- 
stocks from  the  collecting  basin  under  a  head  of  1300  feet.  Current  is  generated  at 
7000  volts  and  transmitted  through  a  tunnel  across  the  boundary  into  Italy,  where, 
at  a  substation  in  Pittamala,  the  voltage  is  stepped  up  to  50,000  for  use  by  the 
Societa  Lombarda,  an  Italian  distributing  company,  to  work  in  parallel  with  their 
well-known  stations  in  Vizzola  and  Castellanza.  This  company  guarantees  the 
use  of  16,000  K.W.  From  the  power  plant  itself  several  aerial  lines  transmit  current 
to  various  other  consumers  in  Switzerland,  and  among  them  it  will  assist  a  small 
power  plant,  still  under  construction  at  Saiento. 

The  5o,ooo-volt  transmission  line,  from  Pittamala  to  the  substation  at  Lomazzo, 
is  88.5  miles  in  length  and  consists  of  two  independent  lines.  A  20,000- volt  trans- 
mission line  branches  off  northward  to  Como  from  the  station  at  Lomazzo,  running 
a  distance  of  30  miles.  An  n,ooo-volt  line  runs  southward  8.5  miles  to  the  steam- 
power  plant  at  Castellanza  for  assisting  or  drawing  current  from  same.  The  bulk 
of  the  current  is  used  in  spinning  and  weaving  mills,  which  begin  operations  at 
7  A.M.;  reaching  the  maximum  in  a  half  hour,  the  load  remains  steady  up  to 
12  o'clock  noon,  dropping  in  thirty  minutes  to  a  few  hundred  kilowatts  and  again 
reaching  the  maximum  at  i  P.M.,  where  it  remains  up  to  7  P.M.  During  the  night 
only  2000  K.W.  are  necessary. 

The  entire  hydroelectric  development  and  transmission  system  is  considered  the 

1  Author's  article,  Electrical  Review,  Aug.  8  and  15,'  1908.  Based  on  data  submitted  by  the  Design- 
ing and  Constructing  Engineers. 


HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 


FiG.  i. — Power  Plant  at  Brusio,  Switzerland.      Showing  Penstocks,  Generating  House  and 
Cable  Tunnel,  Tailrace  Water  Discharge  below  the  Cable  Tunnel. 


TYPICAL  HYDROELECTRIC  PLANTS.  419 

most  up-to-date  in  Europe,  embodying  many  excellent  examples  of  modern  European 
practice. 

Siphon  System.  As  the  level  of  the  water  in  the  lake  will  vary  in  the  neigh- 
borhood of  30  feet,  the  headrace  tunnel  is  located  32.8  feet  below  the  normal  water 
level.  It  was  not  advisable  to  connect  the  tunnel  directly  with  the  bed  of  the  lake, 
therefore  a  siphon  was  installed.  For  this  purpose  a  shaft  was  sunk  about  75  feet 
from  the  water's  edge  and  carried  7.4  feet  below  the  low-water  level.  The  shaft  is 
12  feet  in  diameter,  and  the  portion  below  water  level  was  built  under  air  pressure. 
From  this  shaft,  the  headrace  or  supply  tunnel,  having  a  diameter  of  8.9  feet  at 
this  point,  leads  to  the  collecting  basin. 

The  lake  is  connected  to  this  shaft  by  means  of  a  siphon  tube  6.5  feet  in  diameter 
and  270  feet  horizontal  length  or  body.  The  suction  leg  is  26  feet  long,  provided  with 
a  screen  and  butterfly  valve,  while  the  discharge  leg  is  27.7  feet  long.  The  latter  is 
provided  at  its  bottom  end  with  a  disk  valve  for  regulating  the  flow  of  water.  The 
tube  has  a  pitch  of  5  feet  in  1000,  and  is  provided  at  its  highest  point  with  nozzles;  one 
being  35  inches  in  diameter,  connected  to  a  double-stage  air-pump  for  starting  the 
siphon,  and  the  other,  an  8-inch  connection  for  a  centrifugal  pump,  which  is  used  for 
cleaning  the  siphon  tube,  and  particularly  the  screen.  Instead  of  using  the  air- 
pump  for  starting,  the  centrifugal  pump  may  be  called  upon,  in  which  case  both 
butterfly  and  disk  valve  are  first  closed.  Since  about  180  feet  of  the  horizontal  length 
of  the  siphon  is  located  in  the  lake  under  the  normal  level,  this  portion  of  the  tube, 
made  in  sections  of  36  feet,  was  fitted  at  its  ends  with  blank  flanges,  and  then  floated 
to  its  position  between  piles  and  anchored  to  the  framework  of  the  piling.  The  final 
flange  connections  were  made  by  divers. 

Secondary  Water  Supply.  For  the  purpose  of  damming  the  water  in  the  lake,  six 
sluice  gates  were  built  at  the  outlet,  five  of  these  being  13.12  feet  wide,  and  one  being 
6.56  feet  wide.  The  smaller  one,  which  is  located  lower  than  the  others,  is  used  for 
passing  sand  and  gravel.  Located  at  right  angles  to  the  dam  or  sluice  gates,  is  a  small 
basin  provided  with  a  screen.  A  33-inch  pipe,  provided  with  a  gate,  leads  from  this 
basin  to  the  headrace  tunnel,  800  feet  below,  where  a  shaft  was  sunk  to  receive  the 
pipe;  this  arrangement,  constituting  a  second  water  supply,  was  utilized  in  order  to 
start  the  plant  at  an  early  date.  The  size  of  this  pipe  was  so  chosen,  that  it  might 
later  be  used  as  one  of  the  penstocks  leading  from  the  collecting  basin  to  the  power 
house.  This  pipe  by-passed  the  upper  section  of  the  headrace  tunnel  and  the  siphon 
system,  and  furnished  the  water  supply  during  construction  pending  the  securing  of 
necessary  concessions. 

Headrace.  The  headrace  is  17,056  feet  long,  4920  feet  running  through  moraine 
(a  formation  similar  to  landslides),  and  the  remainder  through  gneiss.  A  portion  of 
the  tunnel,  near  the  collecting  basin,  lies  about  100  feet  deep,  while  the  greatest  por- 
tion of  its  length  lies  some  425  feet  beneath  the  surface.  With  that  portion  of  the 
tunnel  lying  at  the  greatest  depth,  and  running  through  the  gneiss  formation,  no 
difficulty  was  experienced  from  seepage  or  air  leakage,  while  in  the  portion  nearest 
the  surface,  and  where  the  tunnel  runs  through  moraine,  such  difficulty  was  experi- 
enced. For  the  purpose  of  draining  the  seepage  water  and  discharging  the  air, 


420  HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 

ii  lateral  tunnels  were  cut,  having  their  outlet  at  the  nearest  point  on  the  mountain 
slope. 

The  tunnel,  where  cut  through  the  rock,  was  lined  with  concrete  to  a  point  above 
the  water-line,  while  a  portion  of  the  tunnel  above  the  wrater  was  left  unlined.  Where 
the  tunnel  runs  through  the  loose  earth  (moraine),  it  is  constructed  partly  of  con- 
crete and  partly  of  reinforced  concrete;  and  where  it  was  cut  through  the  rock,  pneu- 
matic drills  running  on  tracks  were  employed.  For  this  purpose,  and  for  lighting,  a 
temporary  power  plant  was  installed,  utilizing  the  fall  of  the  Sajento  River.  The 
headrace  was  constructed  of  a  wooden  flume  910  feet  long  and  a  1 2-inch  steel  penstock. 
A  50-H.P.  turbo-generator,  giving  4000  volts,  was  installed;  the  turbine  also  operated 
a  two-step  compressor  supplying  air  at  90  pounds  pressure  through  two  main  pipe 
lines. 

At  three  of  the  seepage-discharge  tunnels,  ventilators  were  installed  during  con- 
struction, while  at  the  remainder,  ventilation  was  produced  by  means  of  branches 
from  the  compressed-air  lines.  Leading  to  the  mouths  of  the  seepage-discharge 
tunnels,  Nos.  6  and  9,  1000  to  1500  feet  above  the  valley,  were  electrical  cable  trans- 
portation lines. 

At  seepage-discharge  tunnel  No.  2,  near  the  take,  an  overflow  system  is  provided 
with  a  sand  and  gravel  trap. 

The  entire  tunnel,  which  is  egg-shaped  with  a  flat  bottom,  has  a  slope  of  2  feet 
in  1000,  and  has  a  sectional  area  of  53.5  square  feet.  The  average  velocity  of  the 
water  in  the  tunnel,  when  partly  filled,  is  6.5  feet  per  second.  Should  the  possibility 
arise  that  in  the  future  the  tunnel  should  be  used  as  a  pressure  tunnel,  for  which  pro- 
vision has  been  made,  the  velocity  of  the  water  will  be  5  feet  per  second. 

As  will  be  noticed  from  the  dimensions  of  the  tunnel  given  above,  the  volume  of 
water  contained  in  same  furnishes  auxiliary  storage  capacity  to  the  collecting  basin. 
Furthermore,  for  a  length  of  one  mile,  the  sectional  area  of  the  tunnel  was  increased, 
and  in  order  to  properly  regulate  the  water  supply  to  the  collecting  basin,  an  additional 
overflow  was  provided  at  seepage-discharge  tunnel  No.  9,  discharging  into  the  above- 
mentioned  Sajento  River.  The  collecting  basin  is  so  dimensioned,  that  with  average 
loads,  the  level  of  the  water  will  be  constant;  while  with  light  loads,  the  level  of  the 
water  will  be  higher;  and  during  the  hours  of  maximum  load,  the  water  level  will  be 
correspondingly  lower. 

Collecting  Basin  and  Penstocks.  The  collecting  basin  is  located  1300  feet  above 
the  valley,  and  is  provided  with  six  penstock  connections  arranged  in  pairs  in  separate 
chambers  provided  with  screens. 

The  usual  practice  of  providing  the  penstocks  with  cut-off  gates  has  not  been 
followed,  owing  to  the  sudden  rise  and  fall  of  the  water.  An  automatic  float  arrange- 
ment for  signaling  the  attendant  was  installed,  operating  by  releasing  a  pawl  and  a 
magnet  clutch,  and  allowing  a  flap  gate  to  close. 

About  100  feet  from  the  collecting  basin  is  a  gate  through  which  pass  the  six  pen- 
stocks. At  the  headgates,  they  have  a  diameter  of  33.5  inches,  and  owing  to  the 
high  head  (1380  feet),  considerable  material  was  saved  by  reducing  the  diameter  at  the 
power  house  to  29.5  inches,  by  telescoping  certain  sections  of  the  penstocks,  thus 


TYPICAL  HYDROELECTRIC  PLANTS. 


A.E?&M. 


giving  at  its  lower  end,  a  water  velocity  of  11.5  feet  per  second.  The  penstocks  are 
made  up  of  rolled  steel,  in  sections  39.36  feet  in  length.  The  heaviest  material 
employed  is  seven-eighths  inch.  The  sections  are  bolted  together  by  the  use  ^f 
movable  flanges.  As  will  be  seen  in  Fig.  i,  the  penstocks  run  down  the  mountain 
slope  at  various  angles,  and  are  anchored  in  solid  concrete  blocks,  there  being  ten 
anchorages.  Between  these  anchorages  the  penstocks  rest  on  concrete  piers,  the 
expansion  being  provided  for  by  the  use  of  slip  expansion  joints.  At  the  headgates 
(Fig.  2),  each  penstock  is  provided  with  a  vent  pipe  about  45  feet  high. 


CAl 


FIG.  2. — Gate  House  for  Penstocks,  Brusio  Plant,  Switzerland. 


Drainage  gates  are  provided  at  the  lower  ends  of  the  penstocks,  for  draining  into 
the  tailrace.  Here  the  six  penstocks  are  interconnected  by  a  cross  pipe  having  two 
outlets,  one  leading  to  the  exciters,  and  the  other  being  provided  with  a  safety  device 
so  that  in  case  of  excess  pressure,  the  "  bursting  plate  "  gives  way  and  relieves  the 
penstocks.  This  cross-pipe  connection  also  serves  the  purpose  of  maintaining  a 
uniform  circulation.  There  are  at  present  installed,  corresponding  to  the  main  turbo- 
units,  five  penstocks.  For  hoisting  the  penstocks  and  other  materials  during  con- 
struction, an  electrically  operated  cable  road  was  installed.  The  drum  and  motor  are 
located  in  an  annex  to  the  gate-house  near  the  collecting  basin. 


422 


HYDROELECTRIC  DEVELOPMENTS  AND  ENGINEERING. 


-d 

i 

T! 


CO 

.s~ 

"•}. 
£ 

PG 


Oi 


I 


I 

i-l 


c 


- 


TYPICAL  HYDROELECTRIC  PLANTS. 


423 


Power  House.  The  power  house  is  located  at  Campocologna  alongside  the  river 
Poschiavino.  The  main  generator  room  is  342  feet  long  by  56.4  feet  wide.  At  the 
side,  there  is  a  single  story  switch  annex  311.5  feet  long  by  10.75  ^eet  wide,  with  a 
three-story  central  section  for  offices. 

Owing  to  the  typography,  heavy  retaining  walls  were  required,  with  deep  and 
expensive  building  foundations.  Up  to  the  main  generating  room  floor,  the  building 
is  of  concrete,  while  the  superstructure  is  of  quarried  stone  and  tile.  The  roof  con- 
struction is  expensive  and  is  as  follows:  Between  I-beam  purlins,  are  large  tile  blocks 
the  undersides  of  which  are  glazed,  to  form  a  finished  ceiling.  These  are  covered  with 
a  one-eighth-inch  layer  of  cement  over  which  are  spread  three  layers  of  so-called  wood- 
cement  (sawdust  and  cement),  between  each  of  which  is  laid  a  layer  of  paper.  Above 
the  layers  of  wood  cement  are  reinforced  concrete  slabs,  an  air  space  of  two  and 
three-eighths  inches  being  left  between  these  slabs  and  the  wood  cement.  These 
precautions  have  been  taken  on  account  of  the  extreme  heat  in  the  summer  time. 

The  building  accommodates  12  main  units,  each  of  3000  to  3500  K.W.  capacity, 
and  4  exciter  units  of  250  HP.  each.  Ten  of  the  main  units  are  at  present  installed. 
A  25-ton  electrically  operated  crane  serves  the  entire  generating  room. 

Turbo-Generator  Units.  There  are  two  different  types  of  turbines  installed  —  the 
impulse  wheel  of  Escher  Wyss  &  Co.,  of  which  there  are  at  present  ten  installed, 
eight  main  and  two  exciter  turbines;  and  the  Girard  turbine  with  partial  admission, 
of  Picard,  Pictet  &  Co.,  of  which  there  are  at  present  installed  two  main  and  two 
exciter  turbines.  The  main  turbines  (3000  K.W.)  run  at  a  speed  of  375  R.P.M.  and 
the  exciters  (150  K.W.)  at  430  R.P.M. ,  and  operate  under  a  head  of  1300  feet.  The 
turbines  are  direct-connected  to  the  water  wheels  by  flexible  insulated  couplings  of 
the  Zodel-Voith  type. 

The  generators  are  3ooo-K.W.,  three-phase,  5o-cycle,  7ooo-volt  machines,  and  are 
designed  for  an  overload  capacity  of  25  per  cent.  They  are  of  the  i6-pole,  revolving 
field  type.  The  poles  are  cast  directly  to  the  field  ring.  The  stator  is  made  in  halves, 
and  has  a  bore  of  10  feet  2  inches,  the  width  being  3  feet  7  inches.  The  bed  plate  is 
made  in  two  sections,  with  the  bearings  cast  on. 

The  Elektrizitats  Gesellschaft  Alioth,  Miinchenstein-Basel,  Switzerland,  manu- 
facturers of  the  generators,  who  installed  also  the  entire  electrical  equipment,  guaran- 
tee the  efficiencies  as  follows: 


Load. 

Power  factor, 
Cos  <t>  =   i. 

Cos  4>  =  0.7. 

Per  cent. 

Per  cent. 

Per  cent. 

0.25 

93-5 

92.0 

o-75 

I.  00 

1.25 

95-° 
96.0 

96-5 

93-5 
94-5 
95-° 

The  four  exciters  are  of  the  6-pole,  ii5-volt,  shunt-wound  type.  They  develop 
150  K.W.  at  450  R.P.M.  Each  exciter  serves  four  generators,  with  twenty-five  per 
cent  overload. 


424 


HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 


Switchgear.  Contrary  to  the  usual  practice  of  centralizing  the  switchgear,  because 
it  was  thought  best  for  the  convenience  of  operation  and  a  material  decrease  in  first 
cost  and  simplification  of  the  wiring  system,  each  generator  has  its  own  switchboard. 
As  will  be  seen  in  Fig.  4,  these  switchboards  are  located  against  the  wall  next  to  the 
switchroom,  and  directly  opposite  each  generator. 

Thus  the  station  is  divided  into  complete  unit  systems.  However,  to  control  all 
.switchboards  from  one  central  point  an  instrument  column  has  been  installed. 


FIG.  4. — Interior  of  Brusio  Power  Plant. 


The  switchboards  are  of  ornamental  design  and  faced  with  white  marble  slabs. 
All  high  tension  parts  of  the  switchgear  are  located  on  the  opposite  side  of  the  wall 
in  masonry  compartments  fitted  with  corrugated  iron  rolling  shutters.  Each  generator 
switchboard  is  equipped  with  the  following  instruments:  two  voltmeters;  one  syn- 
chroscope; with  phase  lamps;  three  ammeters,  one  for  each  phase;  one  three-pole 
oil-switch,  which  may  be  operated  by  hand  or  automatically.  There  are,  further, 
an  ammeter  on  the  central  column,  a  main  current  rheostat  for  excitation,  and  a 
field  discharge  resistance. 

Owing  to  the  non-centralization  of  the  switchgear  system,  it  was  not  considered 
necessary  to  install  a  double  bus-bar  or  ring  system,  so  common  in  Swiss  practice. 
There  is  one  main  and  one  exciter  bus;  both  systems  are  divided  in  the  middle  by 


TYPICAL  HYDROELECTRIC  PLANTS.  425 

sectionalizing  switches.  The  arrangement  is  such  that  a  group  of  three  generators 
may  also  be  independently  excited  and  thrown  upon  separate  bus-bars.  The 
current  from  these  three  generators  is  intended  for  the  valley  of  Brusio  and  for  the 
operation  of  the  Bernian  Railway. 


FIG.  5. — Individual  Generator  Switchboard. 

The  outgoing  feeders,  with  the  exception  of  those  just  mentioned,  are  connected 
at  the  middle  of  the  bus-bars,  which  are  made  up  of  copper  strips,  two  by  three- 
sixteenths  inch  being  sufficient  for  one  generator.  Thus,  where  each  generator 
connection  joins  the  bus-bar  an  additional  layer  has  been  added.  The  bus-bars 
run  the  entire  length  of  the  switchroom,  above  the  aisle  and  close  to  the  ceiling. 
They  are  carried  on  petticoat  insulators  fastened  to  I-beams,  and  are  securely 


426  HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 

anchored  in  the  middle  and  at  the  ends,  so  that  in  case  of  a  severe  short  circuit  the 
different  phases  will  not  be  thrown  together. 

The  exciter  switchboard  (Fig.  8)  is  located  upon  a  platform  in  the  middle  of 
the  generating  room,  opposite  the  exciters.  It  is  provided  with  four  white  marble 
panels,  one  for  each  exciter,  and  upon  each  are  mounted  a  voltmeter,  ammeter, 
knife-switch,  shunt  rheostat,  and  a  reverse  current  circuit-breaker. 

In  front  of  the  exciter  switchboard  is  the  above  mentioned  central  instrument 
column,  upon  which  are  mounted  the  following  instruments:  an  ammeter,  with 
multiple  throw  switch,  to  read  the  current  of  each  generator;  one  voltmeter,  with 
plugs,  for  each  phase;  two  ammeters,  one  for  each  of  the  outgoing  feeder  systems  of 
the  Societa  Lombarda,  and  one  hand  wheel,  operating  a  shaft  to  which  are  connected 
the  shunt  rheostats  of  the  four  exciters.  From  this  column  one  attendant  may 
control  the  operation  of  the  entire  plant. 

Current  Supply.  As  previously  stated,  much  of  the  current  generated  is  trans- 
mitted across  the  boundary  line  into  Italy,  and  it  was  deemed  advisable  to  run  duplicate 
circuits  to  the  substation  at  Piattamala.  Since,  however,  the  valley  is  quite  narrow 
and  atmospheric  discharges  are  of  great  frequency,  a  tunnel  was  built  for  the  purpose 
of  carrying  these  wires  to  the  station. 

The  conductors  leave  the  basement  of  the  switchroom  and  cross  the  River 
Poschiavino  through  a  covered  bridge  (Fig.  i),  where  they  then  enter  the  tunnel 
mentioned.  This  tunnel,  which  runs  to  a  substation,  is  1650  feet  long.  It  is  8.2 
feet  wide  and  9.8  feet  high,  the  top  being  arched. 

Owing  to  the  customs  regulations  between  the  two  countries,  the  tunnel  cannot 
be  entered  from  the  power  house  end.  Entrance  is  obtained,  however,  through  a 
door  visible  from  the  street;  at  the  boundary  line,  the  tunnel  is  closed  off  by  an  iron 
door  separating  the  Italian  and  Swiss  sections. 

The  accompanying  cross  section,  Fig.  9,  illustrates  the  scheme  of  arranging 
the  conductors  in  the  tunnel.  They  consist  of  copper  bars  0.25  square  inch  in 
section,  which  are  carried  on  petticoat  insulators  supported  on  channel  irons  pro- 
jecting from  the  side  walls  of  the  tunnel.  These  channels  are  spaced  longitudinally 
for  4.9  feet,  with  reinforced  concrete  slabs  spanning  them,  forming  partitions  between 
the  conductors.  The  outgoing  yooo-volt  feeders  tap  the  middle  of  the  bus-bar 
system,  then  are  carried  on  either  side  of  the  tunnel  to  the  substation.  For  the 
protection  of  the  customs  officials,  the  circuits  are  fenced  off  by  removable  wire 
netting. 

Step-up  Station,  Piattamala.  This  station  is  built  in  the  shape  of  a  T,  180.5  ^eet 
long,  68.8  feet  wide,  and  28.2  feet  high,  the  cross  wing  being  92  feet  long  and  42.6  feet 
high.  It  is  designed  to  accommodate  24  single  phase  transformers  having  a  capacity 
of  1250  K.W.  each.  At  present  there  are  thirteen  installed,  with  a  total  normal 
capacity  of  16,250  K.W. 

At  one  end  of  the  transformer  room  is  the  meter  room,  where  the  current  is 
checked  by  the  two  companies.  The  transformers  are  arranged  in  two  rows,  between 
which  are  two  tracks  leading  into  the  inspection  and  repair  room.  This  is  in  the 
middle  of  the  cross  arm  of  the  T,  in  which  there  is  a  lo-ton  traveling  crane.  The 


TYPICAL  HYDROELECTRIC  PLANTS. 


427 


FIG.  6. — Back   of   Individual   Generator 
Switchboard,  Brusio  Plant,  Switzerland. 


FIG.  7. —  Rear  of  Switchboards,  and  Gen- 
erator Busses. 


FIG.  8. — Exciter  Switchboard  and  Control 
Pedestal. 


FIG.  9. — Cross  Section  of  Cable  Tunnel 
leading  across  Boundary,  between 
Power  House,  Brusio,  Switzerland,  and 
Step-up  Station,  Piattamala,  Italy. 


428 


HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 


transformer  switchboard  rooms  are  directly  behind  each  row  of  transformers.  The 
substation  is  divided  into  two  distinct  sections.  The  outgoing  feeders  leave  the 
building  from  the  third  story  of  the  cross  wing. 


FIG.  10. — Step-up  Transformer  Station,  Piattamala,  Italy. 


The  feeder  lines  from  the  power  station  enter  the  substation  from  the  tunnel  on 
the  ground  floor,  as  the  station  is  built  into  the  hillside.  As  two  companies  are 
concerned  in  the  amount  of  current  used,  the  Brusio  Company  supplying  and  the 
Societa  Lombarda  receiving  the  current  for  distribution,  this  room,  on  the  ground 
floor,  is  thoroughly  equipped  with  measuring  instruments,  some  of  which  are  kilowatt 
meters  of  different  makes,  and  are  switched  in  series  in  order  to  check  each  other. 


TYPICAL  HYDROELECTRIC  PLANTS. 


429 


The  switches  are  so  arranged  that  the  current  may  be  thrown  onto  either  row  of 
transformers,  from  either  of  the  two  feeder  lines,  or  the  current  from  both  feeders 
may  be  thrown  on  one  row  of  transformers  only.  The  oil  switches,  in  the  meter 
room,  are  of  the  remote-control,  hand-operated  type.  It  was  not  deemed  advisable 
to  install  automatic  switches,  because  a  sudden  cutting  out  the  whole  load,  which 
might  amount  to  20,000  K.W.,  might  seriously  interfere  with  the  operation  of  the 
plant,  particularly  the  hydraulic  end. 

Above  the  aisle,  between  the  two  rows  of  transformers,  and  extending  the  full 
length  of  the  room,  is  a  mezzanine  floor  carrying  the  feeders  in  two  vertical  rows, 


FIG.  ii. — Switch  Room  and  Step-up  Transformer  Station,  Piattamala,  Italy. 


one  on  either  side  of  the  transformers.  The  phases  of  the  bus-bar  system  are  sepa- 
rated by  concrete  shelves,  the  front  remaining  open.  The  high-tension,  or  50,000- 
volt  bus-bars  run  on  the  mezzanine  floor  above  the  transformer  switchboard  or 
operating  rooms.  These  bus-bars  are  arranged  in  horizontal  rows  separated  by 
concrete  partitions,  but  not  covered. 

The  transformers  are  of  the  Alioth  water-cooled  oil  type,  a  system  of  water  circu- 
lation from  a  spring,  under  a  head  of  26  feet,  being  provided.  The  efficiency  of  the 
transformers  under  actual  test  at  full  load  was  97.5  per  cent;  at  half  load,  96.5  per 
cent.  The  drop  in  voltage  between  no  load  and  full  load,  with  a  power  factor 


430  HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 

cos  <j>  =  i,  is  one  per  cent.  With  cos  <£  =  0.8,  is  2.2  per  cent.  The  greatest  drop  is 
2.8  per  cent. 

Each  transformer  is  contained  in  a  well  ventilated  concrete  compartment,  the 
front  being  provided  with  a  corrugated  iron  rolling  shutter.  The  transformers  are 
provided  with  pinion  wheels,  resting  on  pairs  of  racks,  secured  to  the  floor,  the  transfer 
table  also  being  provided  with  such  racks.  This  device  greatly  facilitates  the  handling 
of  the  transformers,  a  ratchet  being  used  for  moving  them  onto  the  transfer  table,  by 
which  they  are  transported  on  the  track  to  the  inspection  and  repair  room,  where 
the  cores  are  easily  taken  out  by  the  overhead  crane. 

Each  transformer  is  provided  on  the  low-tension  (7000  volts)  side,  with  a  three- 
pole  oil  switch,  while  on  the  high-tension  side  (50,000  volts),  three  oil  switches,  one 
for  each  phase,  are  provided.  These  switches,  interconnected,  are  remote  controlled, 
and  may  be  operated  either  by  hand  or  automatically.  Access  to  the  yooo-volt 
switches,  which  are  protected  by  doors,  can  only  be  had  when  the  current  is  off. 
The  5o,ooo-volt  switches  are  similarly  protected.  All  these  switches  are  accessible 
from  the  aisles  of  the  operating  rooms.  Between  each  group  of  transformers,  sec- 
tionalizing  switches  and  choke  coils  are  provided  for  protection  against  variations 
in  load  caused  by  throwing  the  switches. 

Protecting  Devices.  On  account  of  the  high  tension  and  long  transmission  line, 
the  great  variation  in  altitude  and  consequent  difference  in  temperatures,  and  par- 
ticularly on  account  of  the  frequent  storms  and  atmospheric  discharges,  various 
devices  were  installed  for  protection  against  surges.  For  this  purpose,  the  choke 
coils  above  mentioned  are  placed  on  each  side  of  the  transformers,  and  horn  lightning 
arresters  are  placed  on  the  outgoing  feeders.  The  latter  have  a  gap  of  two  and 
three-eighths  inches  and  are  connected  in  series  with  waterflow  resistances.  The 
choke  coils  consist  of  two  spools,  having  a  brass  core,  upon  which  is  tightly  wound 
a  copper  band  of  sixty  turns,  separated  by  insulating  material,  forming  a  solid,  tightly 
wound  spool,  which  sudden  surges  will  not  distort. 

For  taking  up  lighter  static  and  atmospheric  discharges,  the  more  sensitive  role 
lightning  arresters  were  installed  and  connected  in  series  with  waterflow  resistances. 
Finally,  as  all  surges  will  create  more  or  less  variation  in  pressure,  waterflow  grounders 
are  installed  for  each  phase,  to  maintain  a  uniform  pressure.  This  apparatus  consists 
of  a  nozzle  for  forcing  a  jet  of  water,  under  a  head  of  26  feet  (supplied  from  above- 
mentioned  spring),  against  a  baffle  plate  connected  to  the  line.  The  stream  of 
water  is  three-eighths  inch  diameter  and  28  inches  high,  and  allows  a  leakage  of 
one-tenth  ampere.  Ammeters  are  inserted  in  the  wire  connection  to  this  apparatus, 
in  order  to  detect  failures  in  the  grounding. 

All  lightning  arresters,  as  well  as  the  outgoing  lines,  are  provided  with  disconnect- 
ing switches.  All  metallic  features  of  the  installation  are  interconnected  and  well 
grounded. 

Transmission  Lines.  The  transmission  line  (50,000  volts)  may  be  considered 
the  most  important  in  Europe.  It  consists  of  two  independent  lines,  each  88.5  miles 
long.  As  the  line  runs  over  mountains  and  valleys,  peaks  were  avoided  as  much  as 
possible,  to  escape  the  unavoidable  difficulties  due  to  atmospheric  discharges.  These 


TYPICAL  HYDROELECTRIC  PLANTS. 


431 


lines  cross  three  provinces  and  94  townships,  and  required  the  right  of  way  through 
6000  properties,  the  cost  of  which  averaged  about  $800  per  mile.  The  lines  cross 
ten  railways,  one  tramway,  ten  state  roads  and  120  county  roads. 

From  the  main  substation  at  Piattamala,  the  line  runs  westward  through  the  Adda 
Valley  to  Colico,  thence  along  the  shore  of  Lake  Como  to  Bellano,  from  which  point 
it  runs  in  a  southeasterly  direction  over  the  Valsasina  Plateau.  Palasco,  the  highest 
point  of  the  line,  is  2130  feet  above  sea  level.  From  Valsasina  the  line  runs  in  the 
mountains  of  Lecco  in  a  southwesterly  direction,  and  cross  the  Adda  Valley  with  a 
span  of  720  feet,  this  being  the  lowest  point  of  the  line  (640  feet  above  sea  level). 
From  here,  until  the  first  step-down  station,  at  Lomazzo,  is  reached,  88.5  miles  distant 
from  the  step-up  station  at  Piattamala,  the  run  is  practically  straight.  Eight  and 
one-half  miles  beyond  Lomazzo,  at  Castellanza,  is  another  step-down  station. 


FIG.  12. — Brusio  5o,ooo-volt  Line,  Crossing  Railway. 

The  average  span  is  393  feet.  In  87  cases,  however,  the  span  exceeded  the 
average,  the  longest  span  being  1280  feet,  across  the  Gravina  Valley  at  Colico.  The 
transmission  line  consists  of  two  parallel  rows  of  towers,  from  13  to  16.5  feet  apart, 
of  latticed-girder  construction  embedded  in  concrete.  Each  tower  is  provided  with 
six  brackets,  three  for  present  use  and  three  for  future  extension,  so  that  there  will 
be  eventually  four  separate  three-phase  circuits.  The  porcelain  insulators  are 
supported  on  pins,  fastened  to  oak  and  chestnut  blocks  secured  to  steel  brackets. 
Each  cable  consists  of  nineteen  wires,  2.6  mm.  in  diameter,  the  total  diameter  of  the 
cable  being  14  mm.  (105  square  mm.  area). 


432  HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 

The  towers  are  calculated  for  a  wind  pressure  of  70  miles  per  hour,  allowing  a 
stress  in  the  copper  of  8500  pounds  per  square  inch,  and  on  the  tower  of  17,000 
pounds  per  square  inch. 

Allowance  is  made  for  a  temperature  difference  of  i2o°F.  On  account  of  the 
difference  in  the  spans  and  frequent  changes  in  direction  of  the  lines,  four  different 
types  of  towers  are  employed,  weighing  from  1250  to  2500  pounds  each.  There  is 
a  total  of  3100  towers,  averaging  in  price  $80  each,  including  foundation  and  erection. 
The  two  existing  lines  represent  900  gross  tons  of  copper  and  10,000  insulators  at 
$2.60  each,  including  mounting  and  wooden  blocks.  The  laying  of  the  cables  cost 
$128  per  mile  of  transmission. 

The  transmission  system  is  divided  into  six  sections,  varying  from  8.5  to  25.5 
miles,  and  is  provided  with  section  switches  so  arranged  that  in  case  of  a  break  in  a 
section  of  one  line  the  current  may  be  by-passed  over  the  other.  There  is  a  small 
station  at  each  section,  for  housing  the  sectionalizing  switches,  measuring  apparatus, 
lightning  arresters,  some  of  which  are  of  the  horn  type,  some  of  the  coil  type,  and 
some  are  also  provided  with  water-flow  grounders  as  described  previously. 

At  a  distance  of  65  feet,  and  parallel  with  the  high  tension  lines,  a  telephone 
and  telegraph  line  is  carried  the  entire  length  of  the  transmission  system,  for  the 
exclusive  use  of  the  plant.  There  are  two  wires  carried  on  wooden  poles;  and 
30  stations  costing  $30  each,  while  the  line  costs  about  $380  per  mile. 

Transformer  Station,  Lomazzo.  This  substation  is  located  centrally  in  the  low 
tension  distributing  district.  It  is  built  in  the  form  of  an  I.  The  wing  at  one  end, 
containing  the  apparatus  for  the  incoming  feeders,  is  85  by  30  feet,  and  48  feet  high. 
The  wing  at  the  opposite  end  is  of  the  same  dimensions,  and  contains  the  apparatus 
for  the  outgoing  feeders.  The  middle  member  of  the  building,  containing  the  trans- 
formers, is  55  feet  wide,  60  feet  long,  and  33  feet  high.  The  over-all  dimensions  are 
85  by  1 20  feet. 

The  two  5o,ooo-volt  circuits  enter  the  second  floor  of  one  of  the  wings  in  a  way 
similar  to  the  outgoing  feeders  leaving  the  step-up  station  at  Piattamala.  They  are 
similarly  protected  against  electrical  discharges,  except  that  the  water-flow  lightning 
arresters  are  supplied  with  water  by  a  centrifugal  pump  and  tank  under  a  head  of 
40  feet  instead  of  a  natural  head  from  the  mountain  stream.  The  transformers 
(1250  K.W.  50,000-11,000  volts)  are  arranged  in  two  rows,  similar  to  those  at 
Piattamala,  with  tracks  in  front  of  the  compartments,  of  which  there  are  six  on  each 
side.  There  are  also  six  three-phase  transformers  of  5000  K.W.  each  (11,000-20,000 
volts).  There  are  at  present  installed  only  three  single-phase  and  three  three-phase 
transformers.  While  the  transformers  at  Piattamala  are  of  the  oil-cooled,  water- 
circulating  type,  those  at  this  station  (Lomazzo)  are  of  the  forced  air-cooled  type, 
for  which  two  blowers  are  at  present  installed.  The  final  equipment  demands  four 
blowers,  of  which  two  will  be  kept  in  reserve.  The  blowers  are  motor-driven  and 
discharge  through  air  ducts  located  beneath  the  two  rows  of  transformers.  The 
cores  of  the  transformers  are  not  encased. 

The  fronts  of  the  transformer  compartments  are  provided  with  rolling  shutters; 
ventilators  are  placed  in  the  roof.  Good  results  were  obtained  with  these  trans- 


TYPICAL  HYDROELECTRIC  PLANTS. 


433 


formers,  an  advantage  being  that  the  cores  can  be  easily  inspected.  The  primary 
winding  is  provided  with  taps,  so  that  the  voltage  may  be  reduced  to  35,000.  This 
was  done  so  that  easy  regulation  might  be  secured.  The  tests  show  that  the  efficiency 
at  full  load  is  97  per  cent,  and  at  half  load  96.5  per  cent.  The  pressure  loss  at  full 
load  with  power  factor  of  cos  </>  =  i  is  one  per  cent,  and  with  a  power  factor  0.8  it 
is  3  per  cent.  The  temperature  rise  is  40°  C.  The  high  and  low  tension  sides, 
respectively,  were  tested  to  65,000  and  17,000  volts,  10  minutes  duration.  The  trans- 
formers are  capable  of  standing  an  overload  of  25  per  cent  with  a  total  temperature 


FIG.    13. — 5000-K.V.A.   Open  Type    Air- 
Cooled  Transformer  at  Lomazzo,  Italy. 


FIG.  14 — 5o,ooo-volt.  Switch  Room  at  Sub- 
station, Lomazzo,  Italy. 


rise  of  60°  C.  The  operation  of  the  blowers  is  included  in  the  aboved-named 
efficiencies. 

The  11,000-20,000  volt,  500  K.W.,  three-phase  transformers  have  an  efficiency 
of  97  per  cent  at  full  load  with  a  power  factor  of  cos  <j>  =  i,  while  with  cos  (f>  =  0.8  it  is 
96  per  cent,  and  three-quarters  load  96  per  cent  and  95  per  cent,  while  at  half  load  it 
is  95.5  and  94.5  per  cent.  The  drop  in  pressure  is  1.5  per  cent  with  a  power  factor 
of  cos<£  =  i,  and  3  percent  with  a  power  factor  of  0.8.  The  temperature  rise  is 
50°  C.,  and  the  overload  capacity  is  20  per  cent  for  two  hours. 

Distribution.  The  wiring  diagram  is  made  so  that  under  normal  operating 
conditions  the  line  "A"  will  distribute  ii,ooo-volt  current  in  the  district  about 
Lomazzo,  and  "B"  and  "C"  will  supply  Castellanza.  The  arrangement  is  such 
that  one  bus-bar  system  may  feed  either  of  the  outgoing  lines,  or  that  the  line  "A" 
to  Lomazzo  may  be  fed  from  the  line  "C."  Through  the  line  "C"  ii,ooo-volt 
current  ma^  be  drawn  from  the  steam-power  plant  at  Castellanza  of  the  Societa 


434  HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 

Lombarda,  which  is  a  reserve  for  the  hydraulic  plants  at  Turbigo  and  Vizzola.  It 
will  be  seen  that  with  this  auxiliary  source  of  supply,  in  case  of  emergency,  current 
may  be  sent  through  this  station  (Lomazzo)  and  through  the  station  at  Piattamala 
to  the  hydraulic  plant  at  Brusio. 

A  fourth  line  of  20,0x30  volts  leads  northward  to  Como,  for  which  purpose  the 
three-phase,  1 1 ,000-20,000- volt  transformers  were  installed. 

The  feeders  from  the  50,000-11,000- volt  transformers  lead  to  the  three-pole 
oil  switches  on  the  mezzanine  floor  above  the  aisle,  between  the  two  rows  of  trans- 
formers. The  feeders  to  and  from  the  transformers  are  provided  with  cutout 
switches. 

The  50,000,  11,000,  and  20,000  volt  bus-bars  are  arranged,  according  to  the  space 
available,  in  horizontal  or  vertical  rows,  and  the  phases  separated  by  concrete 
shelves  or  partitions.  These  bus-bar  compartments  remain  uncovered.  The 
2o,ooo-volt  outgoing  feeders  are  protected  like  those  at  the  step-up  station  at 
Piattamala. 

Transformer  Station,  Castellanza.  As  previously  stated,  the  Societa  Lombarda 
possesses  a  steam-power  plant  at  Castellanza,  having  an  equipment  of  two  2500-!!?. 
engines  and  two  5ooo-HP.  steam  turbines,  which  work  in  parallel  with  the  above 
described  hydroelectric  plants  at  Brusio,  Turbigo,  and  Vizzola.  A  temporary  trans- 
former station  has  been  erected  in  the  engine  room  of  this  power  house,  and  contains 
six  single-phase,  I250-K.W.  transformers  arranged  in  groups  of  three. 

The  whole  apparatus,  owing  to  the  small  space  available,  has  been  located  on 
three  floors.  The  transformers,  which  are  of  the  oil,  water-cooled  type,  are  designed 
similarly  to  those  at  Piattamala,  except  for  a  voltage  of  11,000-40,000.  Taps  are 
provided,  so  that  some  coils  may  be  cut  out,  to  secure  a  voltage  of  35,000.  The 
efficiency  of  the  transformers  at  full  load  is  98  per  cent,  and  at  half  load  97  per  cent. 
The  drop  in  pressure  at  full  load  with  a  power  factor  of  cos  <j>  =  i  is  i  per  cent, 
while  with  cos  <f>  =  0.8  it  is  2  per  cent.  The  rise  in  temperature  is  45°  C.,  using 
five  gallons  of  water  in  twenty  minutes  at  15°  C.  They  are  capable  of  standing  an 
overload  of  25  per  cent,  maintaining  the  temperature  of  45°  C.,  and  using  ten  gallons 
of  water,  or  with  a  rise  of  temperature  of  60  degrees,  using  five  gallons  of  water. 
The  transformers  were  tested  at  65,000  volts  for  a  duration  of  ten  minutes. 

As  the  capacity  of  the  steam-power  plant  is  expected  to  be  increased  in  the  near 
future,  an  isolated  transformer  station  is  now  being  erected  alongside  of  this  power 
house,  which  will  accommodate  eighteen  transformers. 

The  entire  installation  was  put  in  operation  within  2.5  years  after  the  organization 
of  the  company,  and  is  giving  most  satisfactory  results,  the  expectation  being  that 
the  maximum  output  will  be  reached  during  this  year. 


TYPICAL  HYDROELECTRIC  PLANTS.  435 

THIRTY    THOUSAND    GENERATOR    VOLTAGE    TRANSMISSION    SYSTEM. 
DALMATIA,    AUSTRO-HUNGARY.1 

The  manufacture  of  carbide  has  been  carried  on  extensively,  for  a  number  of 
years,  in  certain  sections  of  the  Austro-Hungarian  empire,  particularly  in  Dalmatia 
and  Bosnia.  In  order  to  produce  carbide  on  an  economical  scale,  the  question  of 
obtaining  low-rate  electric  current  was  an  essential  one.  This  resulted,  for  a  section 
of  Dalmatia,  in  utilizing  the  Kerka  river  to  such  an  extent  that  this  undertaking  is 
one  of  the  foremost  hydroelectric  developments  of  Austro-Hungary. 

Of  the  many  novel  and  unique  features  embodied  in  the  hydraulic  and  electrical 
end,  the  adoption  of  high-voltage  generators,  feeding  directly  a  twenty-one  mile 
aerial  transmission  system,  at  a  potential  of  30,000,  and  its  simple,  yet  highly  efficient 
protecting  devices  against  atmospheric  discharges,  stand  out  most  prominently. 
This  is  another  Continental  step  in  the  practicability  and  simplicity  of  generating 
current  at  high  voltage,  for  long  transmission  systems,  without  the  aid  of  step-up 
transformers. 

The  river  Kerka  rises  at  the  foot  of  Dinaria  Mountains,  forming  the  boundary 
between  Bosnia  and  Dalmatia,  and  flows  southwesterly,  emptying  into  the  Adriatic 
Sea,  in  the  bay  of  Sebenico,  below  the  town  Scardona.  The  Kerka,  although  com- 
paratively short,  has,  throughout  its  length,  many  scenic  falls,  varying  in  height  from 
25  to  147  feet;  the  latter,  named  after  the  river  Kerka  and  owing  to  their  grandeur, 
are  well  known  to  Dalmatian  travelers. 

The  first  hydroelectric  plant  on  this  river,  and  to-day  still  in  operation,  was  installed 
at  the  Kerka  Falls  in  1894;  a  3OO-HP.  Girad  turbine,  operating  under  a  head  of 
33  feet,  is  bevel-geared  to  a  22O-volt,  42-cycle,  single-phase  generator.  The  voltage 
is  stepped-up  to  3000  volts  and  transmitted  a  distance  of  six  miles,  to  Sebenico,  for 
light  and  power.  With  the  commercial  success  of  carbide  manufacture  by  electric 
current  in  1898  a  second  5oo-HP.  unit  was  added  for  experimental  purposes  in 
connection  with  two  carbide  furnaces. 

The  present  owners  of  the  water  rights,  Societa  per  la  utilizzazione  della  forze 
idrauliche  della  Dalmazia"  of  Trieste,  started  up  a  new  plant  at  Jaruga  in  1903, 
with  two  350O-HP.  double  Francis  turbines,  operating  under  a  head  of  80  feet.  They 
are  directly  connected  to  3ooo-K.V.A.,  42-cycle,  two-phase  alternators,  making 
315  R.P.M.  The  15,000  generator  voltage  is  directly  transmitted,  over  9  mm. 
conductors,  to  the  carbide  works,  some  6  miles  away,  not  far  from  the  town  Sebenico 
where  the  voltage  is  stepped-dewn  to  forty-eight  by  oil-cooled,  water-circulated, 
single-phase  transformers.  The  step-down  station  adjoins  the  carbide  furnaces,  so 
that  the  transmission  line  for  15,000  amperes  is  very  short. 

The  current  from  this  plant  is  consumed  in  eight  carbide  furnaces,  requiring,  on 
the  average,  5000  HP  per  hour  throughout  the  year.  With  the  increased  demand  for 
carbide,  the  factory  has  been  recently  extended  to  accommodate  thirty-two  furnaces, 
consuming,  on  the  average,  32,000  HP.  per  hour  throughout  the  year.  For  this 

1  Author's  article.  Electrical  Review,  Jan.  9,  1909.  Based  on  Data  Submitted  by  the  Designing  and 
Constructing  Engineers. 


436 


HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 


FIG.  i. — Manojlovac  Plant,  Dalmatia,  Austro-Hungary. 

purpose,  a  new  hydroelectric  plant,  of  24,ooo-HP.  capacity,  has  been  installed  at 
Manojlovac  Falls,  near  Kistanje,  some  21  miles  upstream,  above  the  Sebenico 
carbide  works.  This  plant,  together  with  the  above-mentioned  earlier  plants,  was 
designed  and  installed  by  Ganz  &  Co.,  Budapest,  who  also  supplied  all  the  hydraulic, 
mechanical  and  electrical  equipments  of  all  these  plants. 

Near  the  Manojlovac  Falls,  the  river  forms  an  S,  and  in  the  course  of  1.2  miles 
has  a  drop  of  360  feet.     The  flow  varies  greatly;  in  spring,  due  to  snow  thaws, 


TYPICAL  HYDROELECTRIC  PLANTS. 


437 


amounting  to  1700  cubic  feet  per  second,  and  in  exceptionally  dry  summer  season, 
to  but  350  cubic  feet  per  second. 

Manojlovac  Plant.  Just  above  the  mentioned  S,  the  river  forms  a  natural  lake, 
with  an  outlet  over  a  natural  dam,  which  is  tapped  6.5  feet  below  the  crest,  where  the 
inlet  to  the  headrace  is  provided  with  three  sluice  gates.  It  will  be  seen  that  it  was 
unnecessary  to  build  a  dam,  yet  sufficient  water  is  impended  for  dry  season.  The 
headrace  is  5250  feet  long,  and  has  a  slope  of  2  feet  in  1000.  It  has  a  cross-section 
area  of  117  square  feet,  cut  through  the  solid  rock  of  the  mountain.  To  reduce  skin 
friction,  it  is  cement-coated  up  to  the  water  level. 


FIG.  2. — Plan  of  Manojlovac  Plant,  Dalmatia,  Austro-Hungary. 

In  order  to  save  excavation,  two  separate  collecting  basins,  joining  each  other, 
have  been  installed.  As  there  are  four  penstocks,  and  due  to  the  arrangement  of 
the  turbines  in  the  generating  room  (a  right  and  left  hand  turbine  facing  one  another), 
there  are  two  penstock  beds. 

At  the  junction  of  the  headrace  and  collecting  basin  are  fine  screens;  each  inlet 
to  the  penstocks  is  provided  with  a  vertical  swinging  sector-gate,  which  is  hydraulic- 
operated,  the  pressure  being  supplied  by  gravity  from  a  reservoir  situated  on  the 
mountain  slope,  some  165  feet  above  the  collecting  basin.  The  water  for  the 
reservoir  is  supplied  by  a  small  piston  pump  in  the  power  house,  driven  by  a  Pelton 
wheel,  under  a  head  of  328  feet.  By  this  arrangement,  the  piston  pump  has  to  supply 
water  against  a  head  of  about  300  feet.  Should  the  supply  water  fail,  provision  is 
made  to  operate  the  sector  gates  manually  by  worms  and  gears. 

Adjoining  the  collecting  basin  is  a  filtering  system  of  three  gravel  filters,  to  supply 
the  hydraulic  governors  of  the  turbines.  The  water  is  conveyed  to  same  by  means  of 
cast  iron  bell  and  spigot  pipes.  The  water  to  the  filter  system  is  supplied  by  a  small 
channel,  branching  off  from  the  main  headrace.  Thus  the  filtering  is  done  by  gravity, 
instead  of  under  pressure,  as  is  the  case  in  many  European  power  plants,  where  the 


438 


HYDROELECTRIC   DEVELOPMENTS  AND  ENGINEERING. 


connections  to  the  filters  are  made  at  the  foot  of  the  main  penstocks.  Of  course, 
with  the  latter  arrangement,  a  different  kind  of  filtering  system  is  adopted. 

The  penstocks  leave  the  collecting  basin  by  bellmouthed  connections;  just  outside 
of  the  wall  are  vents,  so  that,  should  the  sector  gates  close  before  the  turbines  are 
cut  off,  the  penstocks  will  not  collapse.  Each  penstock  is  558  feet  long,  63  inches 
in  diameter,  having  a  shell  thickness  at  the  top  of  one-fourth  inch  and  at  the  lower 
end,  of  nine-sixteenths  inch.  They  were  shipped  in  sections  19.7  feet  long,  and 
contrary  to  the  usual  practice  of  bolting  same  by  means  of  flanges,  the  sections  are 
riveted  together.  The  penstocks  rest  on  concrete  piers;  the  lower  ends  are  well 
anchored,  while  the  upper  ends  are  provided  with  expansion  joints. 

Generator  Room.  The  turbines  are  of  the  Francis  spiral  type,  provided  with  two 
draft  tubes,  and  operate  under  a  head  of  328  feet,  and,  with  a  water  consumption  of 


FIG.  3. — Interior  of  Manojlovac  Plant,  Dalmatia,  showing  Four  3O,ooo-volt  Generator  Units. 


212  cubic  feet  per  second,  develop,  at  420  R.P.M.,  66,000  HP.  each.  Owing  to  the 
large  units,  the  double  flow  was  adopted  to  obviate  the  side  thrust,  which  in  the  single 
flow  type  is  usually  overcome  by  special  thrust  bearing.  The  counterbalancing  effect 
is  adjusted  by  regulating  the  guide  vanes. 

The  regulation  of  each  turbine  is  accomplished  by  an  hydraulic-actuated  governor, 
which,  when  the  revolutions  exceed  10  per  cent  above  the  normal,  operates  a  trip 
lever,  which  cuts  off  the  supply.  As  the  load  is  entirely  for  the  manufacture  of  carbide, 
a  very  regular  one,  the  governors  come  into  play  practically  only  when  the  turbines 
run  away.  It  requires  three  seconds  to  cut  off  the  supply  from  full  to  no  gate. 

The  generators  of  the  Ganz  &  Co.  type  are  rigidly  coupled  to  the  shafts  of  the 


TYPICAL  HYDROELECTRIC  PLANTS. 

turbines;  they  are  of  a  very  unique  design.  In  order  to  eliminate  step-up  transform 
mers,  the  generators,  which  are  the  three-phase,  42-cycle  type,  are  designed  for 
30,000  volts,  and  at  420  R.P.M.,  with  a  power  factor  0.8,  deliver  5200  K.V.A.  each. 
The  efficiencies  at  full  and  half  load,  with  power  factor  0.8,  are  94  and  91  per  cent, 
respectively.  When  running  with  full  load  and  a  power  factor  0.8,  at  constant  speed 
and  excitation,  a  sudden  dropping  of  the  load  will  cause  the  voltage  to  rise  18  per 
cent.  With  maximum  excitation,  the  windings  will  stand  a  short  circuit  for  two 
minutes. 

The  revolving  field  consists  of  a  cast-steel  ring  shrunk  upon  a  spider  wheel;  twelve 
cast-steel  pole  cores  are  fitted  into  dove-tailed  slots  and  secured  by  conical  bolts. 


.  OF  C/ 


FIG.  4. — 6000  HP.  Unit,  Manojlovac  Plant,  Dalmatia,  Austro-Hungary. 


The  field  windings  consist  of  flat  copper  strips,  wound  on  edge,  and  held  in  place  by 
the  pole  shoe,  which  is  part  of  the  pole  itself.  The  insulation  of  the  coils  consists 
of  paper  sheets,  and  the  whole  is  incased  in  paper  casing,  formed  to  suit  the  coil.  The 
whole  revolving  field,  with  shaft,  weighs  26  long  tons. 

The  armature  frame  consists  of  halves,  which  again  are  split  perpendicular  to 
the  axis,  and  when  bolted  together  form  a  perfect  circular  ring.  It  will  be  observed  in 
the  illustration  that  the  feet  for  the  frame  are  removable;  this  was  provided  for  the 
following  purpose:  the  liability  of  a  breakdown  in  a  high-tension  generator  feeding 
directly  into  an  overhead  transmission  line,  is  greater,  owing  to  atmospheric  dis- 


440  HYDROELECTRIC  DEVELOPMENTS  AND  ENGINEERING. 

charges,  than  one  feeding  an  underground  cable  system,  or  that  of  a  lower-tension 
generator,  feeding  transmission  lines  through  step-up  transformers. 

In  the  pit,  the  generator  frame  rests  on  two  pairs  of  rollers,  by  means  of  which, 
after  the  feet  have  been  removed,  the  whole  frame  can  be  revolved,  and  the  lower 
section  be  brought  on  top  and  removed  by  the  overhead  crane,  should  it  be  necessary 
to  inspect  the  coils  in  the  lower  half  of  the  armature.  By  this  arrangement  it  is  not 
necessary  to  remove  the  revolving  element  of  the  generator. 

The  coils  are  machine  form-wound  in  five  different  shapes.  Each  is  composed 
of  a  rectangular  copper  conductor,  wound  for  twenty-six  per  slot  per  phase.  The 
convolutions  are  insulated  by  several  layers  of  Micanite,  over  which  are  wound 
several  layers  of  insulating  tape.  Connections  to  the  coils  are  made  through  brass 
terminals,  soldered  to  the  ends  of  the  winding. 

Each  generator  has  its  own  exciter  mounted  on  the  overhang  of  the  shaft.  The 
most  striking  feature  of  this  arrangement  is  the  method  by  which  the  exciting  current 
is  led  to  the  revolving  field.  On  the  extensions  of  the  carbon  brush  holders  are 
the  copper  brushes  bearing  on  the  collector  rings  (one  of  which  is  insulated), 
mounted  on  the  shaft,  adjoining  the  commutator.  The  generator  shaft  is  bored 
up  to  the  field;  through  this  hole  the  exciter  current  is  supplied  by  an  insulated 
cable.  The  return  is  through  the  shaft  itself. 

The  generator  bearings  are  37^  inches  long  and  icf  inches  in  diameter,  lined 
with  white  metal,  and  are  water-cooled. 

Switch  Room.  Parallel  to  the  generating  room  in  the  middle  and  sunk  in  the 
opposite  wall,  is  the  switchboard. 

There  are  four  generator  panels,  one  collector  or  totalizing  and  three  outgoing 
panels.  Upon  each  generator  panel  are  mounted,  a  rheostat  for  the  exciter  field; 
lever  for  the  generator  switch;  a  volt  and  ammeter,  also  voltmeter  for  excitation; 
phase  lamps,  synchronism  indicator  and  double  throw  switch  for  parallel  operation. 
The  totalizing  panel  contains  three  ammeters  and  a  totalizing  recording  wattmeter. 
Further,  there  are  three  automatic  switch  devices,  which  open  the  field  circuits  of 
all  exciters,  in  case  of  an  excess  of  generator  voltage  or  current  overload,  or  a  diminu- 
tion of  the  generator  pressure,  and  by  means  of  the  automatic  turbine  regulator,  the 
water  supply  to  the  turbines  is  cut  off. 

Each  feeder  panel  has  an  ammeter  and  a  pilot  switch  for  the  overload  oil  circuit 
breaker. 

Behind  the  switchboard  is  the  switchroom,  the  low  building  above  the  tailrace; 
the  tower  at  the  end  is  for  the  outgoing  lines.  All  the  switches  and  measuring  trans- 
formers for  each  machine  are  placed  in  concrete  cells;  wherever  possible,  the  apparatus 
for  each  phase  is  in  a  separate  cell. 

The  generator  switches  are  of  the  single-pole,  oil  type,  actuated  from  the  switch- 
board by  means  of  cable  and  sheaves.  The  moving  element  of  each  phase  of  a  switch 
is  connected  to  a  common  operating  shaft.  Adjacent  to  the  oil  switch  cells  are 
those  for  the  series  and  potential  transformers,  and  so  continue  for  the  four  generator 
units.  On  the  roof  of  the  cells  are  hook  switches,  also  placed  in  cells.  On  top  of 
these,  is  a  single  set  of  bus-bars;  the  different  phases  are  separated  by  low  partitions. 


TYPICAL  HYDROELECTRIC  PLANTS. 


441 


At  one  end  of  the  bus-bars,  after  the  fourth  unit  connections,  are  three  double 
cells  containing  the  general  station-protecting  devices,  consisting,  for  each  phase  of 
the  busses,  of  a  condenser  submerged  in  oil;  a  horn-gap  provided  with  auxiliary 
gap  and  a  multigap  arrester  shunted  by  a  resistance  placed  in  oil.  From  here  the 
busses  branch  out  into  two  feeders  per  phase  for  the  two  aerial  circuits. 

The  phases  of  each  circuit  are  provided  with  overload  circuit  breakers,  potential 
and  series  transformers  for  the  ammeters  and  relays,  and  hook  switches. 

From  here  the  lines  pass  to  the  upper  floor  of  the  tower,  and  just  before  leaving 
the  building,  each  is  provided  with  the  following  combination  of  lightning  protecting 
devices;  a  choke  coil  with  capacity  cylinder;  a  horn-gap 
with  auxiliary  gap,  by  means  of  which  the  main  gap  can  be 
adjusted  to  a  lower  breakdown  setting  than  the  usual. 
The  horns  are  shunted  by  graphite  resistance-rods;  further, 
a  multigap  arrester  with  shunted  resistance;  finally,  the 
ground  connection  is  made  through  continuous  water- 
flow  grounders,  which  lead  off  light  static  discharges. 
The  conductors  leave  the  building  through  porcelain 
bushings. 

It  will  be  noticed  that  the  protecting  equipment  is 
simple,  yet  very  complete;  this  precaution  had  to  be  taken 
because  the  generators  feed  directly  an  aerial  transmission 
line,  which  leads  through  a  section  of  country  passing  over 
plateaus,  canyons  and  valleys,  very  frequently  visited  by 

violent   thunder  storms  and  other   atmospheric    electrical  JTIG   c Insulator  used  on 

discharges.  30,000- volt  Transmission 

Transmission  System.  Both  circuits  led  to  the  carbide  System,  Manojlovac, 
..  01-  M  T  i  •  j  Dalmatia,  Austro-Hun- 

factory  near  Sebenico,  some  21  miles  distant,  and  carried       „„_., 

gary. 

practically  the  entire  length  on  wooden  poles  spaced  nor- 
mally 108  feet  apart;  the  lowest  conductor  is  some  19  or  23  feet  above  the  ground. 

The  conductors  are  9  mm.  copper  wire,  carried  on  three-piece,  two-petticoat  porce- 
lain insulators,  the  head  diameter  being  7  inches,  the  total  height  being  8.5  inches. 
The  pin  and  first  petticoat  are  held  together  by  a  glaze  of  lead  and  glycerine.  The 
head  or  second  petticoat  rests  on  the  first,  with  an  air  space  between,  formed  by  the 
ribs  on  the  inside  of  the  head.  The  insulators  were  tested  at  80,000  volts,  and  during 
operation  none  have  broken  down. 

Where  the  transmission  line  crosses  small  country  roads,  the  poles  are  placed  on 
either  side  of  the  road,  where  they  are  also  provided  with  grounded  guard  arms, 
so  that  in  case  of  breakage,  the  line  is  grounded;  as  the  spacing  is  so  close,  a 
broken  conductor  cannot  touch  the  ground.  To  take  up  side  stresses  on  turns, 
the  circuits  are  carried  on  A-frames.  To  protect  the  wooden  poles  against  light- 
ning, each  has  a  pointed  castiron  cap  with  a  ground  wire. 

Fig.  6  shows  a  latticed  construction  used  in  crossing  the  highway  and  telegraph 
lines.  The  bottom  and  sides  of  this  steel  construction  are  provided  with  a  wire 
netting. 


442 


HYDROELECTRIC   DEVELOPMENTS   AND  ENGINEERING. 


The  transmission  lines  enter  the  carbide  plant  with  a  similar  lightning  protection 
equipment  as  in  leaving  the  power-house  tower,  with  the  exception  of  the  water-flow 
grounders,  owing  to  the  lack  of  fresh  water. 

After  passing  the  lightning  arresters,  connections  of  the  two  circuits  are  made 
to  a  common  bus-bar  system  by  automatic  oil  circuit  breakers,  and  series  transformers 
with  their  recording  instruments. 

There  are  installed  12  single-phase  oil-cooled  water-circulated  transformers  of 
1500  K.V.A.  each,  stepping-down  the  line  voltage,  which  is  here  26,000,  to  48  volts, 


FIG.  6. — Transmission  Line  crossing  Highway  and  Telegraph.     In   Rear   Carbide  Plant. 
Manojlovac  System,  Dalmatia,  Austro-Hungary. 

used  in  the  carbide  furnaces.  The  wiring  system  is  so  arranged  that  from  the  con- 
trol panel  at  each  furnace,  the  transformer  feeding  same  can  be  thrown  on  to  any 
phase  in  order  to  balance  the  load  of  the  circuit.  Again,  the  division  of  load  between 
the  two  furnaces  of  one  transformer  is  indicated  on  a  differential  meter  expressing 
.the  division  of  lead  in  per  cent. 

There  are  further  two  I50-K.V.A.  26,ooo/33O-volt  three  phase  transformers  to 
operate  auxiliary  apparatus,  such  as  pumps  supplying  salt  water  for  cooling  the 
transformers;  crushers  and  conveyors  for  limestone,  coal  and  carbide;  repair  shops 
and  driving  the  ventilators  of  the  furnaces,  etc. 

The  Manojlovac  plant  has  been  continuously  in  operation  since  the  earlier  part 
of  1907,  and  has  given  entire  satisfaction;  no  trouble  has  been  experienced  with  the 
transmission  line,  or  the  high  tension  generators,  although  the  country  was  frequented 
by  heavy  storms  and  electrical  discharges. 


INDEX 


INDEX. 


A. 

Action  of  horn  gap  lightning  arrester,  310. 
Adaptability  of  wooden  penstocks,  78. 
Air  compressors,  281. 
Aluminum  lightning  arrester,  318. 
American  and  European  hydroelectric  develop- 
ments, 325. 
American  Fork  plant,  penstocks,  85. 

turbine,  130. 
Ammeter,  191. 
Anchors,  71. 
Anchor  bolts,  106. 

insulator,  271. 
Appendix,  325. 

Application  of  lightning  arresters,  312. 
Architectural  features,  107. 
Area  of  circles,  60. 
Arrangement  of  substations,  280. 

B. 

Bar  Harbor,  Ellsworth,  power  plant,  27. 
Basin,  collecting,  56. 
Bear  traps,  35. 
Bearing  power  of  soil,  103. 
Beznau  roller  sluice  gate,  33,  34. 
Bibliography  on  mechanical  equipment  of  power 
plants,  165. 

on  dams,  38. 

on  electrical  equipment  of  power  plants,  211. 

on  headraces,  58. 

on  high  tension  transmission,  278. 

on  hydraulic  developments,  18. 

on  line  protection,  324. 

on  substations,  307. 

on  penstocks,  87. 
Bishop  Creek  plant,  penstock,  84. 
Bolts,  anchor,  106. 
Buildings,  101. 

bearing  power  of  soil,  103. 

character  of  soil,  103. 

concrete  mat  construction,  106. 

excavation,  101. 

foundations,  101,  106. 

piling,  104. 

site  for  building,  101. 


Buijdings  —  Continued 

test  holes,  101. 

test  of  piles,  105. 

weight  of  masonry,  104. 
Bus  bars,  201. 

compartments,  202. 

room,  Lontsch  plant,  203. 

room,  Lucerne  plant,  203. 

Ontario,  340. 

outdoor,  346. 
Butterfly  dam,  34. 
Brusio  plant,  Swiss-Italian,  417. 

collecting  basin,  420. 

current  supply,  426. 

distribution,  433. 

gate  house,  421. 

generators,  423. 

headrace,  419. 

headrace  tunnel,  46. 

insulators,  267. 

open  air  cooled  transformer,  433. 

penstocks,  420. 

penstock  flange,  68. 

penstock  flap,  75. 

power  house,  423. 

protecting  device,  430. 

railway  crossing,  431. 

secondary  water  supply,  419. 

siphon  system,  419. 

step-up  station,  Piattamala,  426. 

substation,  Castellanza,  434. 

substation,  Lomazzo,  432. 

switch  gear,  424. 

tower,  247. 

transmission  lines,  430. 

transmission  tunnel,  427. 

turbines,  423. 

C. 

Canals,  40. 

Cantilever,  Niagara  Crossing,  Ontario,  343. 

tower,  Obermatt,  246. 
Capacity  and  discharge  of  penstock,  63. 
Castellanza  substation,  oil  switches,  209. 
Castelnuovo-Valdarno,  switch  house,  178. 
Channels,  water  velocity,  41-42. 


445 


446 


INDEX. 


Chanoine  dam,  36. 

Chevres  plant,  France,  54. 

Chicago  drainage  canal,  34. 

Choke  coils,  315. 

Circles,  area,  60. 

Circuit  breakers,  209. 

Clamps  and  ties  for  insulators,  265,  273. 

Concrete,  dams,  23. 

mat  construction,  106 
penstocks,  86. 
piling,  105. 

Concreted  wooden  poles,  232. 
Conductors,  method  of  tying,  274. 

wind  pressure,  236. 
Conduits,  40. 

Converter,  field  connections,  298. 
frequencies,  296. 
phase,  298. 
starting,  299. 
Converters,  296. 

compounding,  301. 
hunting,  299. 
reactances,  301. 
Cost  of  current,  3. 

of  developments,  3. 
of  wooden  penstocks,  81,  83. 
Costs,  Uppenborn,  416. 
Couplings,  153. 
Coffer  dam,  26,  29. 
Cooling  of  circulating   water  for  transformers, 

293- 
Collecting  basin,  56. 

basin,  Brusio,  74,  420. 
Colliersville  plant,  90-91. 
Columns,  123. 

Compounding,  rotary  converters,  301. 
Compound  Francis  turbine,  135 
Conductors,  215. 

alternating  current  conductor,  219. 
alternating  current,  problem,  219. 
cables,  copper,  224. 
cables  as,  216. 
characteristics,  217. 
direct  current,  218. 
elasticity  of,  216. 
size,  217. 
spacing,  217. 
strength  of,  215. 
corona  effect,  226. 
direct  current  problem,  218. 
reactance  volts,  table,  223. 
transposition  of  conductors,  226. 
wire  gauges,  comparison,  220. 
wire,  solid  copper,  221,  225. 
stranded  copper,  222. 
weight  and  strength  of,  223. 
Crane,  117. 


Crib  dam,  26. 
Cross  arms,  231. 

Curtain  method,  testing  turbines,  159. 
Cylindrical  dams,  36. 
gate,  56. 

D 

Dams,  19. 

behavior  of  resultants,  24. 
bibliography,  38. 
butterfly,  34 
Chanoine,  36. 
Charlotte,  352. 
coffer,  26,  29. 
concrete,  23. 
crib,  26. 
cylindrical,  36. 
earth  construction,  32. 
earth,  Necaxa,  31. 
Ellsworth,  28. 
gravity,  19. 
Heimbach,  394. 
masonry,  22. 
Necaxa,  372. 
needle,  36. 
Patapco,  25. 

reinforced  concrete  core,  32. 
steel  frame,  30. 
submerged  power  plant,  25. 
timber,  29. 
Dixville,  32. 

Deflector  in  headrace,  49. 
Designing  staff,  16. 
Detail  of  drum  gate,  55. 
Development,  economy,  15. 

first  costs,  15. 

Developments,  investigation,  3. 
Direct  current  switchboards,  187. 
Doors,  1 1 6. 
Draft  tubes,  141. 

Drawings,  charge  of  extra  work,  16. 
checking,  16. 
and  specifications,  16. 
Drum  gate,  54. 
detail,  55. 
Duluth  substation,  no. 


E 

Earth  dam,  Necaxa,  31. 
Economy  in  development,  15. 
Economical  spans,  250. 
Electrolysis  prevention,  127. 
Electrolytic  arrester,  320. 
Electrical  equipment  of  power  plants,  167. 
bibliography,  211. 


INDEX. 


447 


Elevators,  116. 

Ellsworth  dam,  28. 

El  Oro,  substation,  381. 

Equalizing  chambers,  76. 

European  methods  of  testing  turbine,  157. 

Exciters,  173. 

wiring  diagram,  198. 

Expansion  slip  joints  for  penstocks,  71-72. 
Expansion  joints  of  structural  steel,  124. 


F. 

Field  office,  17. 

Financial  aspect,  362,  403. 

Fishways,  37. 

Flanges,  66-75. 

Flashboards,  36. 

Floors,  in,  124. 

Floating    foundation    for    transmission    tower, 

344- 

Flow  of  river,  10. 
Fluid  arresters,  318. 
Flumes,  masonry,  42. 

timber,  42,  44. 
Flywheels,  153. 
Flywheel  alternator,  169. 

with  internal  stationary  armature,  169. 
Foundations,  106. 

for  steel  towers,  236,  263. 
Four-legged  towers,  240,  344. 

twin  tower,  239. 
Forest  preservation,  4. 
Forebays,  88,  329. 
Francis  turbines,  131. 
Frequencies,  173,  364. 
Frequency  changers,  303. 

meter,  193. 
Friction  in  steel  penstocks,  61. 

in  tunnels,  45. 

in  wooden  penstocks,  80. 


Gate  house,  74,  331,  420. 

valves,  57. 

Gates  and  racks,  47. 
Generators,  167. 

auxiliaries,  332. 

30,000  volt,  175. 

leads,  i74,332- 

umbrella  type,  168. 

Brusio,  423. 

Charlotte,  355. 

Heimbach,  397. 

Kykkelsrud,  389, 

Manojlovac,  438. 

Necaxa,  376. 


Generators  —  Continued 

Ontario,  332. 

Uppenborn,  407. 
Geneva  plant,  114. 
Georgia  plant,  89. 
Gola  lightning  protection,  314. 
Governors,  143. 

Bell,  145- 

Escher  Wyss,  144. 

Lombard,  146. 

Glocker-White,  147,  149. 

Replogle,  148,  150. 
Governmental  reports,  13. 
Gross  horsepower  of  falling  water,  7. 
Gradient,  hydraulic,  7. 
Gravity  dams,  19. 

Great  Falls  plant,  Southern  Power  Company, 
Charlotte,  N.  C.,  348. 

auxiliary  power,  367. 

dam,  352. 

financial  aspect,  362. 

frequency,  364. 

generators,  355. 

high  tension  room,  359. 

insulator,  364. 

lightning  protection,  360. 

oil  switches,  360. 

penstocks,  80. 

power  development,  map,  350. 

power  house,  355. 

secondary  power,  367. 

spillway,  348. 

towers,  362. 

transformers,  358. 

transmission  feeder  circuit,  361. 
lines,  360,  366. 

system,  map,  349. 

turbines,  352. 

voltage,  365. 

wiring  diagram,  356. 
Guard  wire,  231. 
Guys,  232. 

H. 

Hafslund,  deflector  and  rack,  49. 

Hamilton  cataract  turbine,  140. 

Hauser  Lake,  dam,  30. 

Heimbach  plant.     See  also  Urfttalsperre,  113. 

Heimbach  plant,  wiring  diagram,  199. 

tower,  246. 
Head,  loss,  6. 
Headrace,  arrangement,  39-40. 

bibliography,  58. 

Brusio,  419. 

Heimbach,  395. 

Kykkelsrud,  382. 

scheme,  39. 


448 


INDEX. 


Headrace  —  Continued 

Sillwerke,  120. 

tunnel,  Brusio,  46. 

Uppenborn,  405. 
Heating,  117. 

factors  of  radiating  surface,  117. 
High  head  plant,  98. 
Holyoke,  plant,  89. 

tests,  160. 

test  flume,  161. 
Horn  gaps,  311. 
Horn-gap  construction,  313. 

setting,  313. 

Horsepower,  gross,  of  falling  water,  7. 
Hunting  of  converters,  299. 
Hydraulics,  5. 

fundamental  formulae,  6. 

principal  formulae,  6. 
Hydraulic  gradient,  7. 

pipes,  riveted,  65. 

relief  valve,  148. 

I. 

Induction  generator,  167. 

regulator,  301. 
Innsbruck  plant,  174. 
Installation  of  multigap  arresters,  317. 
Instrument  pedestal,  185. 
Insulators,  265. 

anchor,  271. 

Charlotte,  364. 

Manojlovac,  441. 

Necaxa,  380. 

Paderno  and  Brusio,  267. 

strain,  271. 

suspended,  268. 

Swiss  and  Italian,  266. 

Uppenborn,  410. 
Insulator  pins,  272-274. 
Insulator  tie  and  clamp,  265,  273. 
Insulating  and  rolling  support,  271. 
Investigation  of  developments,  3. 
Iron  sluice  gates,  54. 
Italian  insulators,  266. 

steel  tower,  247. 

J 

Jajce  plant,  penstock  anchor,  70. 

wedge  shaped  expansion  joint,  72. 


K. 

Kaiserwerke,  penstock  support,  71. 
Kern  River  plant,  97-99. 
insulators,  265. 


Kern  River  Plant  —  Continued 

penstock,  66. 
Kykkelsrud  plant,  Norway,  102,  382. 

exciter  units,  388. 

generators,  389. 

headrace,  382. 

power  house,  386. 

substation,  Hafslund,  392. 

switchboard  room,  390. 

transformer  room,  390. 

transmission  line,  391. 

turbines,  386. 


L. 

Lavatories,  119. 

Laws  of  hydraulics,  5. 

Leaders,  roof,  116. 

Length  of  economical  spans,  261. 

Lighting,  119. 

Lightning  arresters,  309. 

fluid,  318. 

horn  type,  311. 

location,  323. 

multigap,  315. 

principle,  309. 
Lightning  discharges,  309. 
Line  protection,  309-360. 

bibliography,  324. 

disconnecting  switches,  275. 

stresses,  251. 
Location  of  arresters,  323. 

of  substations,  280. 
Loch  Leven  plant,  penstock,  run,  73. 
Lockport  substation,  Ontario,  345. 
Lontsch  plant,  bus  bar  room,  203. 
Loss  of  head  in  penstock,  6,  61,  62. 
Low  head  plants,  90. 
Lucerne,  cantilever  tower,  246-248. 

plant,  112. 

bus  bar  room,  203. 

turbine,  144. 

wiring  diagram,  200. 
Lyon  plant,  France,  56. 


M. 

Manojlovac  plant,  Dalmatia,  435. 
building,  437. 
drainage  area,  436. 
exciters,  440. 

generators,  30,000- volt,  175,  438. 
highway  crossing,  442. 
insulators,  441. 
lightning  arresters,  442. 
line  protection,  441. 


INDEX. 


449 


Manojlovac  plant  —  Continued 

switch  room,  440. 

transformers,  442. 

transmission  poles,  441. 

transmission  system,  441. 

turbines,  438. 
Masonry,  dams,  22. 

flumes,  42. 

weight,  104. 
Material,  building,  in. 
McCall  Ferry  plant,  92-94. 
Mechanical  equipment  of  power  plants,  129. 

bibliography,  165. 
Medium  head  plant,  91,  131. 
Meter,  Venturi,  u. 

water  current,  n. 
Method  of  plotting  discharge  of  rivers,  12. 

of  plotting  river  bed,  13. 
Medium  head  plants,  91. 
Miner's  inch,  8. 

Molinar  plant,  Spain,  method  of  cooling  circu- 
lating water,  293. 

Montreal  substation  frequency  changers,  304. 
Morgan  Fall,  Georgia,  dam,  22. 
Mountain  lakes,  siphoning,  47. 
Motor  generators,  302. 
Motor  generating  station,  Vienna,  302. 
Multigap  arresters,  315. 
Muskegon  no,ooo-volt  insulator,  270. 

tower,  no,ooo-volt,  249. 


N. 

Necaxa  plant,   Mexico,  369. 

building,  374. 

conductors,  381. 

dams,  31,  372. 

development,  map,  370. 

drainage  area,  272. 

generators,  376. 

insulators,  380. 

oil  switches,  380. 

penstocks,  372. 

penstock  flange,  69. 

transmission  system,  380. 

substation,  El  Oro,  381. 

switching  room,  377. 

switchboard,  181,  380. 

towers,  380. 

transformers,  377. 

turbines,  376. 

wiring  diagram,  197. 

wiring  system,  377. 
Needle  dam,  36. 
New  York  Central  Towers,  245. 
Niagara  crossing,  342. 


Niagara  crossing  tower,  240. 

Niagara,   Lockport   and   Ontario   development, 

327- 

Niagara  Falls,  327. 
Niagara  Falls  Power  Company  plant,  48,  93,  95, 

97,  107,  109. 


O. 


Obermatt,  cantilever  tower,  246. 

plant,  112. 

wiring  diagram,  200. 

switch  room,  176-177. 
Oil  filtering  tanks,  154. 

piping,  156. 

pumps,  156. 

required,  154. 

rheostat,  312. 

switches,  204. 
Oiling  system,  154. 
Ontario  plant, 

bus  bars,  340. 

bus  bars,  outdoor,  346. 

cantilever,  Niagara,  crossing,  343. 

circuit  breaker,  6o,ooo-volt,  347. 

control  room,  340. 

distributing  station,  338. 

exciters,  332. 

floating  foundation  for  transmission  tower, 

344- 

forebay,  329. 
four-legged  tower,  344.  • 
gate  house,  331. 
generator  auxiliaries,  332. 
generators,  332. 
generators,  leads,  332. 
high  tension  room,  339. 
insulator  and  pin,  273. 
low  tension  room,  339. 
Niagara  crossing,  342. 
oil  switch  compartment,  207. 
Oneida  tower,  243. 
open  air  fuses,  343. 
outdoor  bus  bars,  346. 
penstocks,  330. 
power  house,  332. 
screen  house,  330. 
substation,  Lockport,  345. 
transformer  room,  339. 
transmission  line,  341. 
three-legged  towers,  341. 
turbines,  332. 
wiring  diagram,  196. 
wiring  system,  339. 
Outdoor  bus  bars,  Ontario,  346. 
disconnecting  switch,  276. 


450 


INDEX. 


Open  air  fuses,  Ontario,  343. 
Overload  relays,  209. 
voltage  relay,  211. 

P. 

Paderno  insulator,  268. 
Painting  of  structural  steel,  127. 
Part  I,  i. 
Part  II,  215. 
Part  III,  323. 
Patapco  dam,  25. 

plant,  174. 
Penstocks,  59. 

anchor,  70-71. 

air  cushion,  76. 

American  Fork  plant,  85. 

bibliography,  87. 

Brusio,  74,  420. 

flanges,  66,  67,  68,  69,  71,  75. 

flap,  75. 

head  loss,  61,62. 

Kern  River  plant,  66. 

Loch  Leven,  73. 

Necaxa,  372. 

Ontario,  330. 

protection,  76. 

run,  59. 

reinforced  concrete,  86. 

shell,  strength,  64. 

size,  59. 

slip  joints,  71,  72. 

steel  construction,  64. 

support,  hinged,  71. 

vents,  50. 

wooden,  Bishop  Creek,  84. 
Piles,  tests,  105. 
Piling,  104. 
Pin  insulators,  265. 
Piping,  oil,  156. 
Poles  and  towers,  tests,  238. 
Poles,  —  see  wooden  poles. 
Pole  and  tower  construction,  228. 
Porcelain  base  insulator  pin,  272. 
Portability  of  steel  towers,  237. 
Poschiavo  siphon  system,  47. 
Power  factor  meter,  192. 
Power  plants,  88. 

Bar  Harbor  plant,  Ellsworth,  27. 

Brusio,  Swiss-Italian  plant,  417. 

Colliersville  plant,  90, 91. 

Georgia  plant,  89. 

Great  Falls  plant,  348. 

Holyoke  plant,  89. 

Kern  River  plant,  97,99. 

Kykkelsrud-Hafslund  plant,  Norway,  382. 
Lyon  plant,  France. 


Power  plants  —  Continued 

Manojlovac  plant,  Dalmatia,  435. 

McCall  Ferry  plant,  92,  94. 

Necaxa  plant,  Mexico,  369. 

Niagara  Falls  Power  Company's  plant,  93, 

95,  97- 

Ontario  plant,  309. 
Puget  Sound  plant,  180. 
Schaffhausen  Low  Head  plant,  132. 
Shawinigan  plant,  92. 
Sill  plant,  Tirol,  120. 
Snoqualmic  plant,  100. 
Stuttgart  plant,  no. 
Toronto  plant,  96. 

Uppenborn  plant,  Munich,  Germany,  403. 
Urfttalsperre    plant,    Heimbach,    Germany, 

393- 

Winnipeg  plant,  89. 
Preservation  of  wooden  poles,  231. 
Preservation  of  forest,  4. 
Pressure  tunnels,  45. 
Principle  of  arresters,  309. 
Profile  of  rivers,  13. 
Properties  of  timber,  53. 
Protection  of  penstocks,  76. 
Pumps,  oil,  156. 


R. 


Racks  and  gates,  47. 
Railway  crossing,  Brusio,  431. 
Reactance,  converters,  301. 
Regulating  devices,  143. 
Regulation  of  generators,  170. 
Reinforced  concrete,  dams,  23. 

penstocks,  86. 

poles,  232. 

tower,  234. 
Relief  valve,  153. 

Remote  control  switchboards,  185. 
Reports,  governmental,  13. 
Reservoirs,  56. 
Reverse  current  relay,  211. 
Revolving  armature  generator,  169. 

field  alternator,  170. 
Rheostats,  193. 

River  bed,  method  of  plotting,  13. 
River,  flow,  10. 
Rivers,  method  of  plotting  discharge,  12. 

profile,  13. 

velocity  of  flow,  7. 
Riveted  hydraulic  pipes,  65. 
Rochester  dead  end  tower,  242. 
Rolling  support  for  long  spans,  271. 
Roof  truss,  122. 
Rotary  converter  connections,  291. 


INDEX. 


451 


S. 


Saddles  for  penstocks,  72. 

Sag  at  different  temperatures,  252. 

Sandtraps,  57. 

Screens,  49. 

Screen,  detail,  51. 

Screen  house,  48,  330. 

Scholes,  D.  R.,  paper  on  transmission  line  towers 

and  economical  spans,  253. 
Secondary  power,  Charlotte,  367. 
Second-feet,  13. 

Section  house,  Uppenborn,  414. 
Section  switches,  274. 
Seepage  in  tunnels,  45. 
Setting  of  horn  gaps,  313. 
Shawinigan  plant,  92,  176,  179. 
Siegwart  concrete  poles,  233. 
Siphoning  lakes,  47. 
Siphon  system,  46,  419. 
Site  for  buildings,  101. 
Size  of  bus  bars,  201. 

of  units,  280. 
Sleet  on  conductors,  236. 
Sluice  gate,  Stoney,  33-34. 
Sluice  gates,  iron,  54. 

wooden,  50-52. 
Snoqualmie  Falls  plant,  100. 
Soil,  bearing  power,  103. 

character  of,  103. 

Spacing  of  bands  on  wooden  penstocks,  78. 
Spans  economical,  250. 

economical  length,  261. 
Spier  Fall,  dam,  22. 
Specifications  and  drawings,  16. 
Specification  of  steel  towers,  243. 
Spillways,  57. 
Spillway,  Charlotte,  348. 
Spoon  wheel  turbine,  144. 
Stairways,  116. 
Standpipes,  76. 
Stansstad  substation,  115. 
Starting  of  converters,  299. 
Steel,  frame  dam,  30. 

insulator  pin,  272. 

penstocks,  59. 

penstock,  friction,  61. 

pipe  towers,  233. 
Steel  tower,  cantilever,  246. 

foundations,  236,  263. 

Heimbach,  246. 

New  York  Central,  245. 

Oneida,  243. 

specifications,  243. 

Syracuse,  240,  241. 
Steel  towers  and  poles,  tests,  238. 

for  suspended  insulators,  249,  250. 


Steel  towers  and  poles  —  Continued 

two-legged,  237. 

wind  pressure,  235. 
Steel  transmission  towers,  235. 
Steghof  substation,  general  arrangement,  285. 
Stoney  roller  sluice  gate,  33,  34. 
Strain  insulators,  application,  271. 
Strength  of  Douglas  fir,  81. 

of  penstock  shell,  64. 
Structural  steel,  122. 

character  of  steel,  125. 

column  bases,  123. 

crane  column,  124. 

expansion  joints,  124. 

fiber  stresses,  125. 

floors,  124. 

inspection,  127. 

painting,  127. 

prevention  of  electrolysis,  127. 

typical  columns,  123. 

typical  roof  trusses,  122. 

workmanship,  126. 
Substations,  280. 
Substation,  arrangements,  280. 

bibliography,  307. 

Castellanza,  434. 

drainage,  281. 

Duluth,  no. 

Heimbach,  401. 

Hirschau,  411,  415. 

Hafslund,  Kykkelsrud,  390. 

location,  280. 

Lomazzo,  432. 

Piattamala,  426. 

Stansstad,  115. 

Steghof,  285. 

Steghof,  motor  generator,  303. 

switchboard  panel,  305. 

switch  gear,  307. 

typical  arrangement,  283. 

ventilation,  281. 

Waterbury,  281. 
Superstructure,  107. 
Survey,  Geological,  United  States,  13. 
Suspended,  insulator,  268. 

insulator  tower,  249-250. 
Swiss-Italian  steel  tower,  247. 
Swiss  insulators,  266. 

penstock  flanges,  66,  67. 

switching  room  arrangement,  183,  184,  186. 

typical  bus  bar  and  wiring  system,  195. 

wiring  practice,  195. 
Switchboards,  176. 

bus  bars  chambers,  190. 

combined  panel,  187. 

D.  C.  board,  187. 

desk,  type,  185. 


452 


INDEX. 


Switchboards  —  Continued 

exciter  or  D.  C.  panel,  186. 

high  tension  A.  C.  boards,  191. 

instrument  bench,  186. 

low  tension  A.  C.  board,  188. 

oil  switch  arrangement,  190. 

panel  switchboard,  183. 

pedestal,  or  column  type,  185. 

types  of  switchboards,  182. 

wagon  panel,  188,  189,  414. 
Switchboard,  equipment,  191. 

gallery,  116. 
Switch  gear,  Brusio,  424. 

for  substations,  307. 

Necaxa,  380 

Ontario,  356. 

panels  for  substations,  305. 

Uppenborn,  407. 
Switching  room,  176. 

Heimbach,  399. 

Kykkelsrud,  390. 

Manojlovac,  440. 

Necaxa,  377. 

Puget  Sound,  180. 
Synchronizing,  192. 
Syracuse  45-foot  tower,  240-241. 
Systems  of  wiring,  diagram,  194. 

T. 

Tailrace  measurement,  159. 
Tanks,  supply,  156. 
Taylor's  Fall,  insulators,  265. 
Telephone,  Uppenborn,  416. 
Telluride  plant,  139. 
Test  of  American  woods,  53. 
Test  holes,  101. 
Tests  of  transmission  poles  and  towers,  238. 

of  reinforced  concrete  poles,  233. 
Testing  turbines,  157. 
Three-legged  towers,  240-341. 
Thrust  bearing,  137. 
Ties  and  clamps  for  insulators,  265,  273. 
Timber  dam,  29. 

flumes,  42,  44. 

properties,  53. 
Tivoli  plant,  121. 

Tofwehult-Westerwik  rolling  support,  271. 
Torchio  lightning  protection,  314. 
Toronto  plant,  96. 
Tower,  dead  end,  Rochester,  242. 

reinforced  concrete,  234. 
Towers,  Charlotte,  362. 

Necaxa,  380. 

steel  pipe,  233. 
Transmission, 

feeder  circuit,  Charlotte,  361. 


Transmission  —  Continued 

high  tension,  bibliography,  279. 
lines,  Brusio,  430. 

Charlotte,  360-366. 

Heimbach,  401. 

Kykkelsrud,  391. 

Ontario,  341. 

stresses,  251. 

towers    and    economical   spans,   253. 
poles,  Manojlovac,  441. 

—  see  wooden  poles, 
system,  Manojlovac,  441. 

Necaxa,  380. 
Uppenborn,  410. 
towers,  Uppenborn,  412. 

—  see  steel  towers, 
transformers,  Manojlovac,  442. 
tunnel,  Brusio,  427. 

Transformation  of  water  power,  i. 
Transformers,  286. 
air  cooled,  293. 
air  required  for,  294. 
arrangement  of  air  blast,  294. 
Charlotte,  358. 
characteristics  of,  287. 
connections  of,  290. 
core  type,  286. 
delta  vs.  Y  connection,  290. 
efficiency  of,  289. 

forced  oil-cooled  transformers,  293. 
method  of  connecting  transformers  to  rotary 

converters,  291. 
oil  circulation  for  cooling,  292. 
oil  cooled,  292. 
regulation  of,  288. 
shell  type,  286. 
transformer  connections,  290. 
characteristics,  287. 
efficiency,  289. 
Necaxa,  377. 
oil  circulation,  292. 
open  air  cooled  Brusio,  433. 
regulation,  288. 
room,  Kykkelsrud,  390. 
room,  Ontario,  339. 
types  of,  286. 
Uppenborn,  407. 
Traps,  bear,  35. 
Trenches,  41. 

Trenton  Water  Fall  plant,  79. 
Tretzo  tower,  241. 
Tunnels,  friction,  45. 
pressure,  45. 
seepage,  45. 
Turbines,  129. 

accessories,  152. 


INDEX. 


Turbines  —  Continued 

Brusio,  423. 

Charlotte,  352. 

curtain  carriage  testing,  159. 

European  methods  of  testing,  157. 

graphical  registrator,  158. 

high  head  turbines,  138. 

Holyoke  testing  flume,  160. 

Heimbach,  397. 

Kykkelsrud,  386. 

low  head,  130. 

medium  head,  131. 

Manojlovac,  438. 

Necaxa,  376. 

Ontario,  332. 

testing,  157. 

Uppenborn,  406. 
Two-legged  tower,  Gaucin-Seville,  Spain,  237. 

tower,  Moosburg,  237. 

towers,  type  used  in  Switzerland  and  Italy, 

237- 
Typical  arrangement  of  headrace,  39,  40. 

of  substations,  283. 
Types  of  oil  switches,  204. 

steel  towers,  259. 

switchboards,  182. 

U. 

Umbrella  type  generator,  168. 
United  States  Geological  Survey,  13. 
Uppenborn  plant,  Germany,  403. 

costs,  416. 

generators,  407. 

generating  plant,  406. 

headrace,  404. 

horn-gaps,  415. 

insulators,  410. 

lightning  arrester  station,  411. 

lightning  protection,  409. 

section  house,  414. 

sluice  gates,  405. 

substation,  Hirschau,  411-415. 

switch  gear,  407. 

telephone,  416. 

transmission  system,  410. 

transmission  towers,  412. 

transformers,  407. 

turbines,  406. 

wall  outlet,  408. 

water  flow  grounders,  413. 
Urfttalsperre,  Heimbach  plant,  Germany,  393. 

dam,  394. 

financial  aspecr,  40;, 

generators,  397. 

headrace,  395. 


Urfttalsperre,  Heimbach  plant  —  C 
power  house,  396. 
substations,  401. 
switching  room,  399. 
transmission  lines,  401. 
turbines,  397. 

V. 

Vacuum  relief  valve,  77. 
Vandoise  penstock  relief  valve,  77. 
Velocity  of  flow  in  rivers,  7. 
Ventilating  of  power  plants,  118. 
Ventilation  of  substations,  281. 
Venturi  meter,  u. 
Vents  for  penstocks,  50. 
Vienna  motor  generator  station,  302. 
Voltage,  173. 

of  converter  and  frequency,  296. 
Voltmeter,  191. 

W. 

Walls,  in. 

Wall  outlets,  typical,  276-278. 

outlet,  Uppenborn,  408. 
Water,  current  meter,  n. 

flow  grounders,  Uppenborn,  413. 

flow  grounders,  321. 

power  transformation,  i. 

velocity  in  channels,  41-42. 
Waterbury  substation,  281. 
Wattmeter,  191. 
Weight  of  masonry,  104. 
Weir  dam,  8. 
Weirs,  construction,  9. 

quantity  of  water  passing  over,  9. 
Windows,  116. 
Wind  pressure  on  conductors,  236. 

on  steel  towers,  235. 
Winnipeg  plant,  89. 
Wiring  diagrams,  194. 

Charlotte,  356. 

for  exciters,  198. 

Heimbach  plant,  199. 

Necaxa  plant,  197. 

Obermatt  plant,  200. 

Ontario  plant,  196. 

of   a  single   generator   and   step-up   trans- 
former, 201. 

Waterbury,  substation,  306. 

wiring  system,  Ontario,  339. 
Wooden  flumes,  42. 

piling,  105. 

penstocks,  78. 

comparative  costs,  83. 


wiv.  OF  a 


454 


INDEX. 


Wooden  penstocks  —  Continued 

connection  to  smaller  pipes,  82. 
construction,  84. 
cost,  81. 
durability,  80. 
friction,  80. 
spacing  of  bands,  78. 
poles,  228. 

"A"  frame  tower,  230. 
cross  arms,  231. 
for  three-phase  circuit,  229. 
kind  of  wood,  229. 


Wooden  Poles  —  Continued 
life  of,  231. 
preservation,  231. 
strength,  229. 

50,000  volts,  Taylor's  Falls,  228. 
pole  line  construction,  232. 
pole  guys,  232. 
pole,  concreted,  232. 
sluice  gates,  50,  52. 
Woods,  test  of  American,  53. 
Working  strain  of  penstock  bands,  70. 
Workmanship  on  structural  steel,  126. 


Uniform  with  "Hydroelectric  Developments  and  Engineering." 
8x11  inches.     473  Pages.     500  Illustrations.     80  Tables.     $5.00  Net. 


STEAM-ELECTRIC  POWER 

PLANTS 


BY 

FRANK   KOESTER 


CONTENTS:  —  Problems,  Efficiency  and  Cost  of  Plants.  Location.  General  Layout. 
Coal  Storage.  Condenser  Water  Supply.  Excavation  and  Foundations.  Steel  Work.  Archi- 
tectural Features.  Boilers.  Mechanical  Stokers  and  Grates.  Coal.  Combustion.  Draught. 
Smoke  Flues.  Chimneys.  Boiler  Feed  Water.  Feed  Water  Heater.  Superheaters.  Super- 
heated Steam.  High  Pressure  Piping.  Low  Pressure  Piping.  Prime  Movers.  Reciprocating 
Engines.  Turbines.  Condensers.  Pumping  Machinery.  Oiling  System.  Electrical  Equipment. 
The  Design  of  Small  Light  and  Power  Plants.  Testing  Power  Plants.  Descriptive  Discussion 
of  Five  Typical  American  and  European  Light  and  Power  Plants.  Principal  Dimensions  and 
Data  of  Recently  Constructed  Light  and  Power  Plants.  Tables  per  K.  W.  Capacity.  Series 
of  Tables.  

Recommended  by  the  technical  journals,  to  experts  and  advanced  engineers. 
Adapted  as  text  by  leading  universities. 


SOME  OPINIONS 


"  The  book  represents  a  lot  of  diligent  work,  much  research,  and  investigation  ; 
it  is  fully  up  to  the  high  standard  of  the  author,  who  has  an  international  reputa- 
tion in  the  engineering  profession."  —  Electrical  Review, 

"  This  book  will  undoubtedly  take  a  high  place  among  classical  works  of  the 
industry  ;  it  is  evidently  the  result  of  an  exceptional  experience,  such  as  falls  to  the 
lot  of  very  few  engineers." —  The  Electrician. 

"  It  would  be  difficult  to  mention  any  detail  that  is  not  touched  upon."  —  Power 
and  The  Engineer. 

"  A  very  considerable  amount  of  information.  —  The  Engineering  Digest. 

"  Probably  no  other  volume  contains  so  much  information." — The  Engineering 
Record. 

"To  a  great  extent  a  classic  on  the  subject."  — Engineering  Times. 

"Considerable  value  to  any  student  of  power  engineering."  —  Sibley  Journal. 

"  It  is  the  work  of  a  very  experienced  engineer ;  everybody  interested  in  power 
plants  should  have  this  book."  —  Zeitschrift  des  Vereines  deutscher  Ingenieure. 

"A  valuable  guide  to  modern  practice."  —  Engineering. 

"  A  comprehensive  and  useful  volume."  —  Engineering  Review. 

"  It  is  a  conscientious  guinea's  worth."  —  Electrical  Times. 

D.  VAN  NOSTRAND  COMPANY 

PUBLISHERS  AND   BOOKSELLERS 

23  MURRAY  AND  27  WARREN  STREETS        =        =        NEW  YORK 


' 


LIST    OF    WORKS 


ON 


ELECTRICAL  SCIENCE 

PUBLISHED   AND   FOR  SALE   BY 

D.  VAN  NOSTRAND  COMPANY, 

23  Murray  and  27  Warren  Streets,  New  York. 


*  WRITE  FOR  COMPLETE  96  PAGE  CATALOG,  GRATIS 


ABBOTT,  A.  V.  The  Electrical  Transmission  of  Energy.  A  Manual  for  the 
Design  of  Electrical  Circuits.  Fifth  Edition,  enlarged  and  rewritten. 
With  many  Diagrams,  Engravings  and  Folding  Plates.  8vo.,  cloth, 
675  pp Net,  $5.00 

ADDYMAN,  F.  T.  Practical  X-Ray  Work.  Illustrated.  8vo.,  cloth,  200 
pp Net,  $4.00 

ALEXANDER,  J.  H.  Elementary  Electrical  Engineering  in  Theory  and  Prac- 
tice. A  class-book  for  junior  and  senior  students  and  working  electricians. 
Illustrated.  12mo.,  cloth,  208  pp $2.00 

ANDERSON,  GEO.  L.  Handbook  for  the  Use  of  Electricians  in  the  operation  and 
care  of  Electrical  Machinery  and  Apparatus  of  the  United  States  Seacoast 
Defenses.  Prepared  under  the  direction  of  Lieut. -General  Commanding  the 
Army.  Illustrated.  8vo.,  cloth,  161  pp $3 .00 

ARNOLD,  E.  Armature  Windings  of  Direct-Current  Dynamos.  Extension  and 
Application  of  a  general  Winding  Rule.  Translated  from  the  original  Ger- 
man by  Francis  B.  DeGress.  Illustrated.  8vo.,  cloth,  124  pp $2.00 

ASHE,  SYDNEY  W.  Electricity  Experimentally  and  Practically  Applied.  422 
illustrated.  12mo.,  cloth,  375pp. Net,  $2.00 

ASHE,  S.  W.,  and  KEILEY,  J.  D.  Electric  Railways  Theoretically  and  Practi- 
cally Treated.  Illustrated.  12mo.,  cloth.  ^ 

Vol.  I.     Rolling  Stock.     Second  Edition.     285  pp Net,  $2 . 50 

Vol.  II.     Substations  and  Distributing  Systems.     296  pp Net.  $2.50 


2  LIST  OF   WORKS  ON  ELECTRICAL  SCIENCE. 

ATKINSON,  A.  A.  Electric  and  Magnetic  Circulations.  For  the  use  of  Electrical 
Engineers  and  others  interested  in  the  Theory  and  Application  of  Electricity 
and  Magnetism.  Third  Edition,  revised.  Illustrated.  8vo.,  cloth,  310  pp. 

Net,  $1 . 50 

ATKINSON,  PHILIP.  The  Elements  of  Dynamic  Electricity  and  Magnetism.  Fourth 

Edition.  Illustrated.  12mo.,  cloth,  405  pp $2 .00 

Elements  of  Electric  Lighting,  including  Electric  Generation,  Measurement, 
Storage,  and  Distribution.  Tenth  Edition,  fully  revised  and  new  matter 

added.  Illustrated.  12mo.,  cloth,  280  pp $1 .50 

Power  Transmitted  by  Electricity  and  Applied  by  the  Electric  Motor,  including 
Electric  Railway  Construction.  Illustrated.  Fourth  Edition,  fully  revised 
and  new  matter  added.  ]2mo.,  cloth,  241  pp $2 .00 

AYRTON,  HERTHA,     The  Electric  Arc.     Illus.     8vo.,  cloth,  479  pp..  .  .Net,  $5.00 

W.  E.  Practical  Electricity.  A  Laboratory  and  Lecture  Course.  Illus- 
trated. 12mo.,  cloth,  643  pp $2.00 

BAKER,  J.  T.  The  Telegraphic  Transmission  of  Photographs.  63  Illustrations. 
12mo.,  cloth,  155  pp Net,  $1.25 

BEDELL,  FREDERICK.  Direct  and  Alternating  Current  Manual.  Assisted  by 
C.  A.  Pierce.  Second  Edition,  enlarged.  Illustrated.  8vo.,  cloth,  365  pp. 

In  Press 

BEDELL,  F.  &  CREHORE,  ALBERT  C.  Alternating  Currents.  An  analytical  and 
graphical  treatment  for  students  and  engineers.  Fifth  Edition.  112  illus- 
trations. 8vo.,  cloth,  325  pp Net,  $2.50 

ELAINE,  ROBERT,  G.  The  calculus  and  Its  Applications.  A  practical  treatise  for 
beginners  especially  engineering  students.  79  illustrated.  12mo.,  cloth, 
330  pp Net,  $1.50 

BIGGS,  C.  H.  W.  First  Principles  of  Electricity  and  Megnetism.  Illustrated. 
12mo.,  cloth,  495  pp $2.00 

BONNY,  G.  E.  The  Electro-Plater's  Hand  Book. rX  A  Manual  for  Amateurs 
and  Young  Students  on  Electro-Metallurgy.  Fourth  Edition,  enlarged. 
61  illustrations.  12mo.,  cloth,  208  pp $1 .20 

BOTTONE,  S.  R.  Magnetos  For  Automobilists  How  Made  and  How  Used.  A 
handbook  of  practical  instruction  on  the  manufacture  and  adaptation  of 
the  magneto  to  the  needs  of  the  motorist.  Second  Edition,  enlarged. 
52  Illustrations.  12mo.,  cloth,  188  pp Net,  $1 .00 

Electric  Motors,  How  Made  aud  How  Used.  Illustrated.  12mo.,  cloth. 
168  pp 75  cents 

BOWKER,  WM.  R.  Dynamo,  Motor,  and  Switchboard  Circuits  for  Electrical 
Engineers  :  A  practical  book  dealing  with  subject  of  direct,  alternating, 
and  polyphase  circuits.  Second  Edition,  greatly  enlarged.  130  illustrations. 
8vo.,  cloth,  180  pp Net,  $2 .00 

BROADFOOT,  S.  K.  Motors,  Secondary  Batteries  and  Accessory  Apparatus.  Illus- 
trated. 16mo.,  cloth.  (Installation  Manuals  Series) In  Press 


LIST  OF  WORKS  ON  ELECTRICAL  SCIENCE.  3 

CARTER,  E.  T.  Motive  Power  and  Gearing  for  Electrical  Machinery;  a  treat- 
ise on  the  theory  and  practice  of  the  mechanical  equipment  of  power 
stations  for  electric  supply  and  for  electric  traction.  Second  Edition,  revised. 
Illustrated.  8vo.,  cloth,  700  pp Net,  $5.00 

CHILD,  CHAS.  T.  The  How  and  Why  of  Electricity:  a  book  of  information  for 
non-technical  readers,  treating  of  the  properties  of  Electricity,  and  how 
it  is  generated,  handled,  controlled,  measured,  and  set  to  work.  Also 
explaining  the  operation  of  Electrical  Apparatus.  Illustrated.  8vo., 
cloth,  140  pp $1  00 

CLARK,  D.  K.  Tramways,  Their  Construction  and  Working.  Second  Edition. 
Illustrated.  8vo.,  cloth,  758  pp $9.00 

COOPER,  W.  R.  Primary  Batteries:  their  Theory,  Construction,  and  Use.  131 
Illustrations.  8vo.,  cloth,  324  pp Net,  $4.00 

The  Electrician  Primers.  Being  a  series  of  helpful  primers  on  electrical 
subjects,  for  the  use  of  students,  pupils,  artisans,  and  general  readers. 
Second  Edition.  Illustrated.  Three  volumes  in  one.  8 vo.,  cloth,  Net,  $5  00 

Vol.  I.— Theory  Net,  $2  .00 

Vol.  II.— Electric  Traction,  Lighting  and  Power Net,  $3.00 

Vol.  III.— Telegraphy,  Telephony,  etc Net,  $2.00 

CROCKER,  F.  B.     Electric  Lighting.     A.  Practical  Exposition  of  the  Art  for  the 
use  of  Electricians,  Students,  and  others  interested  in  the  Installation  or 
Operation  of  Electric-Lighting  Plants. 
Vol.  I. — The  Generating  Plant.     Sixth  Edition,  entirely  revised.      Illustrated. 

8vo.,  cloth,  482  pp $3.00 

Vol.  II. — Distributing  System  and  Lamps.     Sixth  Edition.     Illustrated.     8vo., 

cloth,  505  pp $3 .00 

and  ARENDT,  M.     Electric  Motors:    Their  Action,  Control,  and  Application. 

160  Illustrations.    8vo.,  cloth,  296  pp Net,  2.50 

and  WHEELER,  S.  S.     The  Management  of  Electrical  Machinery.     Being  a 

thoroughly  revised  and  rewritten  edition  of  the  authors'  "  Practical  Manage- 
ment of   Dynamos   and    Motors."     Eighth   Edition.     Illustrated.      16mo., 

cloth,  232  pp Net,  $1 .00 

GUSHING,  H.  C.,  Jr.     Standard  Wiring  for  Electric  Light  and  Power.     Illustrated. 

16mo.,  leather,  156  pp $1 .00 

DAVIES,  F.  H.     Electric  Power  and  Traction.     Illustrated.     8vo.,  cloth,  293  pp 

(Van  Nostrand's  Westminster  Series.) Net,  $2 . 00 

DAWSON,  PHILIP.      Electric    Traction  on  Railways.      610  Illustrations.      8vo., 

half  leather,  891  pp Net,  $9.00 

DEL  MAR,  W.  A.   Electric  Power  Conductors.  69  illustrations.  8vo.,  cloth,  330  pp. 

Net,  $2.00 

DEVEY,  R.  G.  Mill  and  Factory  Wiring.  Illustrated.  16mo.,  cloth.  (Installa- 
Manuals  Series) In  Press 

DIHGER,  Lieut.  H.  C.  Handbook  for  the  Care  and  Operation  of  Naval  Machinery. 
Second  Edition.  Illustrated.  16mo.,  cloth,  302  pp Net,  $2.00 


4  LIST    OF  WORKS  ON   ELECTRICAL  SCIENCE 

DYNAMIC  ELECTRICITY;  Its  Modern  Use  and  Measurement,  chiefly  in  its  appli- 
cation to  Electric  Lighting  and  Telegraphy,  including:  1.  Some  Points  in 
Elect. ic  Lighting,  by  Dr.  John  Hopkinson.  2.  On  the  Treatment  of  Elec- 
tricity for  Commercial  Purposes,  by  J.  N.  Schoolbred.  3.  Electric-Light 
Arithmetic,  by  R.  E.  Day,  M.E.  Fourth  Edition.  Illustrated.  16mo., 
boards,  166  pp.  (No.  71  Van  Nostrand's  Science  Series.) 50  cents 

EDGCUMBE,  K.     Industrial  Electrical  Measuring  Instruments.     Illustrated.     Svo., 
cloth,  227  pp Net,  $2.50 

ERSKINE-MURRAY,  J.  A  Handbook  of  Wireless  Telegraphy  :  Its  Theory  and 
Practice.  For  the  use  of  electrical  engineers,  students,  and  operators. 
Third  Edition,  revised  and  enlarged.  180  illustrations.  8vo.,  cloth,  388 
pp Net,  $3 .50 

Wireless  Telephones  and  How  they  Work.  •  Illustrated.  16mo.,  cloth,  75  pp. 

$1.00 

EWING,  J.  A.  Magnetic  Induction  in  Iron  and  other  Metals.  Third  Edition,  revised. 
Illustrated.  8vo.'  cloth,  393  pp Net,  $4.00 

FISHER,  H.  K.  C.,  and  DARBY,  W.  C.  Students'  Guide  to  Submarine  Cable  Test- 
ing. Third  Edition,  enlarged.  Illus.  8vo.,  cloth,  326  pp Net,  $3.50 

FLEMING,  J.  A.     The  Alternate-Current  Transformer  in  Theory  and  Practice. 

Vol.  I.:  The  Induction  of  Electric  Currents.  Fifth  Issue.  Illustrated.  8vo., 
cloth,  641  pp Net,  $5 .00 

Vol.11.:  The  Utilization  of  Induced  Currents.  Third  Issue.  Illustrated. 

8vo.,  cloth,  587  pp Net,  $5.00 

—  Propagation  of  Electric  Currents  in  Telephone  and  Telegraph  Circuits. 
Illustrated.  12mo.,  cloth In  Press 

Handbook  for  the  Electrical  Laboratory  and  Testing  Room.  Two  volumes. 

Illustrated.  8vo.,  cloth,  1160  pp.  Each  vol Net,  $5.00 

FOSTER,  H.  A.  With  the  Collaboration  of  Eminent  Specialists.  Electrical  Engi- 
neers' -Pocket  Book.  A  handbook  of  useful  data  for  Electricians  and 
Electrical  Engineers.  With  innumerable  Tables,  Diagrams,  and  Figures. 
The  most  complete  book  of  its  kind  ever  published,  treating  of  the  latest 
and  best  Practise  in  Electrical  Engineering.  Sixth  Edition,  completely 
revised  and  enlarged.  Fully  Illustrated.  Pocket  Size.  Leather.  Thumb 
Indexed.  1636  pp $5.00 

FOWLE,  F.  F.  The  Protection  of  Railroads  from  Overhead  Nransmission  Line 
Crossings.  35  illustrations.  12mo.,  cloth,  76  rp Net,  $1.50 

FRENDEMACHER,  P.  W.  Electrical  Mining  Installations.  16mo.,  cloth.  (In- 
stallation Manuals  Series) In  Press 

GANT,  L  W.  Elements  of  Electric  Traction  for  Motormen  and  Others.  Illustrated 
with  Diagrams.  8vo.,  cloth.  217  pp Net,  $2.50 

GERHARDI,  C.  H.  W.  Electicity  Meters;  their  Construction  and  Management. 
A  practical  manual  for  central  station  engineers,  distribution  engineers 
and  students.  Illustrated.  8vo.,  cloth,  337  pp Net,  $4.00 


LIST   OF   WORKS  ON  ELECTRICAL   SCIENCE.  5 

GEAR,  H.  B.  and  WILLIAMS,  P.  F.  Electric  Central  Station  Distribution 
Systems.  Their  Design  and  Construction.  139  illustration.  12mo.,  cloth. 
352  pp Net,  $3.00 

GORE,  GEORGE.  The  Art  of  Electrolytic  Separation  of  Metals  (Theoretical  and 
Practical).  Illustrated.  8vo.,  cloth,  295  pp Net,  $3 . 50 

GRAY,  J.  Electrical  Influence  Machines:  Their  Historical  Development  and 
Modern  Forms.  With  Instructions  for  making  them.  Second  Edition, 
revised  and  enlarged.  With  105  Figures  and  Diagrams.  12mo.,  cloth, 
296  pp $2 . 00 

GROTH,  L.  A.  Welding  and  Cutting  Metals  by  Aid  of  Gases  or  Electricity.  124 
illustrations.  8vo.,  cloth,  280  pp Net,  $3.00 

HAMMER,  W.  J.  Radium,  and  Other  Radio  Active  Substances;  Polonium,  Actin- 
ium, and  Thorium.  With  a  consideration  of  Phosphorescent  and  Fluo- 
rescent Substances,  the  properties  and  applications  of  Selenium,  and  the 
treatment  of  disease  by  the  Ultra-Violet  Light.  With  Engravings  and 
Plates.  8vo.,  cloth,  72  pp $1 .00 

HARRISON,  N.  Electric  Wiring  Diagrams  and  Switchboards.  Illustrated.  12mo., 
cloth,  272  pp $1 .50 

HASKINS,  C.  H.  The  Galvanometer  and  its  Uses.  A  Manual  for  Electricians 
and  Students.  Fifth  Edition,  revised.  Illus.  16mo.,  morocco,  75  pp. .  .$1 .50 

HAY,  ALFRED.  Principles  of  Alternate-Current  Working.  Second  Edition. 

Illustrated.  12mo.,  cloth,  390  pp $2.00 

Alternating  Currents;  their  theory,  generation,  and  transformation.  Second 

Edition.  1 178  Illustrations.  8vo.,  cloth,  319  pp Net,  $2 . 50 

An  Introductory  Course  of  Continuous-Current  Engineering.  Illustrated. 
8vo.,  cloth,  327  pp Net,  $2.50 

HEAVISIDE,  0.  Electromagnetic  Theory.  Two  Volumes  with  Many  Diagrams. 
8vo.,  cloth,  1006  pp.  Each  Vol Net,  $5.00 

HEDGES,  K.  Modern  Lightning  Conductors.  An  illustrated  Supplement  to  the 
Report  of  the  Research  Committee  of  1905,  with  notes  as  to  methods  of 
protection  and  specifications.  Illustrated.  8vo.,  cloth,  119  pp.  .Net,  $3.00 

HOBART,  H.  M.  Heavy  Electrical  Engineering.  Illustrated.  8vo., cloth,  338 
pp Net,  $4.50 

Electricity.  A  text-book  designed  in  particular  for  engineering  students. 

115  illustrations.  43  tables.  8vo.,  cloth,  266  pp., Net,  $2.00 

Design  of  Static  Transformers.     12mo In  Press 

HOBBS,  W.  R.  P.  The  Arithmetic  of  Electrical  Measurements.  Withn  umerous 
examples,  fully  worked.  Twelfth  Edition.  12mo.,  cloth,  126  pp..  50  cents 

HOMANS,  J.  E.  A  B  C  of  the  Telephone.  With  269  Illustrations.  12mo., 
cloth,  352  pp $1 .00 

HOPKINS,  N.  M.  Experimental  Electrochemistry,  Theoretically  and  Practically 
Treated.  Profusely  illustrated  with  130  new  drawings,  diagrams,  and 
photographs,  accompanied  by  a  Bibliography.  Illustrated.  8vo  ,  cloth, 
29S  pp Net,  $3 .00 


6  LIST  OF  WORKS  ON  ELECTRICAL  SCIENCE. 

HOUSTON,  EDWIN  J.  A  Dictionary  of  Electrical  Words,  Terms,  and  Phrases. 
Fourth  Edition,  rewritten  and  greatly  enlarged.  582  Illustrations.  4to.. 
cloth Net,  $7.00 

A  Pocket  Dictionary  of  Electrical  Words,  Terms,  and  Phrases.     12mo.,  cloth, 
950  pp .Net,  $2.50 

HUTCHINSON,  R.  W.,  Jr.  Long-Distance  Electric  Power  Transmission:  Being 
a  Treatise  on  the  Hydro-Electric  Generation  of  Energy;  Its  Transformation, 
Transmission,  and  Distribution.  Second  Edition.  Illustrated.  12mo., 
cloth,  350  pp Net,  $3 .00 

and  IHLSENG,  M.  C.  Electricity  in  Mining.  Being  a  theoretical  and  prac- 
tical treatise  on  the  construction,  operation,  and  maintenance  of  electrical 
mining  machinery.  Illustrated.  12mo.,  cloth In  Press 

INCANDESCENT  ELECTRIC  LIGHTING.  A  Practical  Description  of  the  Edison 
System,  by  H.  Latimer.  To  which  is  added:  The  Design  and  Operation  of 
Incandescent  Stations,  by  C.  J.  Field;  A  Description  of  the  Edison  Electro- 
lyte Meter,  by  A.  E.  Kennelly;  and  a  Paper  on  the  Maximum  Efficiency  of 
Incandescent  Lamps,  by  T.  W.  Ho  well.  Fifth  Edition.  Illustrated. 
16mo.,  cloth,  140  pp.  (No.  57  Van  Nostrand's  Science  Series.). . .  .50  cents 

INDUCTION  COILS:  How  Made  and  How  Used.  Eleventh  Edition.  Illustrated. 
16mo.,  cloth,  123  pp.  (No.  53  Van  Nostrand's  Science  Series.).  .  .50  cents 

JEHL,  FRANCIS.  The  Manufacture  of  Carbons  for  Electric  Lighting  and  Other 
Purposes.  Illustrated.  8vo.,  cloth,  232  pp Net,  $4 . 00 

JOHNSON,  J.  H.  Arc  Lamps  and  Accessory  Apparatus.  Illustrated.  16mo., 
cloth.  (Installation  Manuals  Series) In  Press 

JONES,  HARRY  C.     The  Electrical  Nature  of  Matter  and  Radioactivity.     Second 
Edition,  completely  revised.     12mo.,  cloth,  212  pp $2 .00 

KAPP,  GISBERT.  Electric  Transmission  of  Energy  and  its  Transformation, 
Subdivision,  and  Distribution.  A  Practical  Handbook.  Fourth  Edition, 
thoroughly  revised.  Illustrated.  12mo.,  cloth,  445  pp $3.50 

KAPP,   GISBERT.     Alternate-Current   Machinery.      Illustrated.       16mo.,     cloth, 

190   pp.     (No.  96  Van  Nostrand's  Science  Series.) 50  cents 

Dynamos,     Alternators,     and     Transformers.     Illustrated.     8vo.,    cloth,    507 
pp $4.00 

KELSEY,  W.  R.  Continuous-Current  Dynamos  and  Motors,  and  their  Control; 
being  a  series  of  articles  reprinted  from  the  "  Practical  Engineer,"  and  com- 
pleted by  W.  R.  Kelsey,  B.Sc.  With  Tables,  Figures,  and  Diagrams.  8vo., 
cloth,  439  pp $2.50 

KEMPE,  H.  R.  A  Handbook  of  Electrical  Testing.  Seventh  Edition, 
revised  and  enlarged.  285  Illustrations.  8vo.,  cloth,  706  pp.  .  .  .Net,  $6.00 

KENNEDY,    R.     Modern    Engines    and    Power    Generators.     Illustrated.     4to., 

Electrical    Installations    of    Electric    Light,   Power,   and   Traction    Machinery. 

Illustrated.     8 vo. ,  cloth,  5  vols.     The  Set,  $15. 00 Each,  $3 . 50 


LIST  OF  WORKS  ON  ELECTRICAL  SCIENCE.  7 

KENNELLY,  A.  E.  Theoretical  Elements  of  Electro-Dynamic  Machinery.  Vol  I. 
Illustrated.  Svo.,  cloth,  90  pp $1 .50 

KERSHAW,  J.  B.  C.  The  Electric  Furnace  in  Iron  and  Steel  Production.  Illus- 
trated. 8vo.,  cloth,  74  pp Net,  $1 . 50 

Electrometallurgy.     Illustrated.     8vo.,  cloth,  303  pp.     (Van  Nostrand's  West- 
minster Series.) Net,  $2 . 00 

KINZBRUNNER,  C.  Continuous-Current  Armatures;  their  Winding  and  Con- 
struction. 79  Illustrations.  8vo.,  cloth,  80  pp Net,  $1 .50 

Alternate-Current  Windings;    their  Theory  and  Construction.     89  Illustrations. 
8vo.,  cloth,  80  pp Net,  $1 .50 

KOESTER,  F.  Hydroelectric  Developments  and  Engineering.  A  practical  and 
theoretical  treatise  on  the  development,  design,  construction,  equipment  and 
operation  of  hydroelectric  transmission  plants.  500  illustrations.  4to., 
cloth,  475  pp Net,  $5.00 

Steam-Electric  Power  Plants.     A  practical  treatise  on  the  design  of   central 

light  and  power  stations  and  their  economical  construction  and  operation. 
Fully  Illustrated.     4to.,  cloth,  455  pp Net,  $5 . 00 

LARNER,  E.  T.  The  Principles  of  Alternating  Currents  for  Students  of  Electrical 
Engineering.  Illustrated  with  Diagrams.  12mo.,  cloth,  144  pp. Net,  $1.50 

LEMSTROM,  S.  Electricity  in  Agriculture  and  Horticulture.  Illustrated.  8vo., 
cloth Net,  $1 .50 

LIVERMORE,  V.  P.,  and  WILLIAMS,  J.  How  to  Become  a  Competent  Motorman: 
Being  a  practical  treatise  on  the  proper  method  of  operating  a  street-railway 
motor-car;  also  giving  details  how  to  overcome  certain  defects.  Second 
Edition.  Illustrated.  16mo.,  cloth,  247  pp Net,  $1 .00 

LOCKWOOD,  T.  D.  Electricity,  Magnetism,  and  Electro-Telegraphy.  A  Prac- 
tical Guide  and  Handbook  of  General  Information  for  Electrical  Students, 
Operators,  and  Inspectors.  Fourth  Edition.  Illustrated.  8vo.,  cloth, 
374  pp $2 . 50 

LODGE,  OLIVER  J.  Signalling  Across  Space  Without  Wires:  Being  a  description 
of  the  work  of  Hertz  and  his  successors.  Fourth  Edition.  Illustrated.  8vo., 
cloth,  156  pp Net,  $2 .00 

LORING,  A.  E.  A  Handbook  of  the  Electro-Magnetic  Telegraph.  Fourth  Edition, 
revised.  Illustrated.  16mo.,  cloth,  116  pp.  (No.  39  Van  Nostrand's 
Science  Series.) 50  cents 

LUPTON,  A.  PARR,  G.  D.  A.,  and  PERKIN,  H.  Electricity  Applied  to  Mining. 
Second  Edition.  With  Tables,  Diagrams,  and  Folding  Plates.  8vo.,  cloth, 
320  pp Net,  $4.50 

MAILLOUX,     C.     O.     Electric     Traction    Machinery.     Illustrated.     8vo.,     cloth. 

In  Press 


8  LIST  OF   WORKS  ON  ELECTRICAL  SCIENCE. 

MANSFIELD,  A.  N.  Electromagnets:  Their  Design  and  Construction.  Second 
Edition.  Illustrated.  16mo.,  cloth,  155  pp.  (Van  Nostrand's  Science 
Series  No.  64) 50  cents 

MASSIE,  W.  W.,  and  UNDERBILL,  C.  R.  Wireless  Telegraphy  and  Telephony 
Popularly  Explained.  Illustrated.  12mo.,  cloth,  82  pp Net,  $1 .00 

MAURICE,  W.  Electrical  Blasting  Apparatus  and  Explosives,  with  special 
reference  to  colliery  practice.  Illustrated.  8vo.,  cloth,  167  pp.  .Net,  $3.50 

MORECROFT,  J.  H.  and  HEHRE,  F.  W.  A  Short  Course  in  Testing  of  Electrical 
Machinery.  Illustrated.  8vo.,  cloth In  Press 

MORGAN,  ALFRED  P.  Wireless  Telegraph  Construction  for  Amateurs.  153  illus- 
trations. 12mo.,  cloth,  220  pp Net,  $1.50 

NIPHER,  FRANCIS  E.  Theory  of  Magnetic  Measurements.  With  an  Appendix 
on  the  Method  of  Least  Squares.  Illustrated.  12mo.,  cloth,  94  pp. $1 .00 

NOLL,  AUGUSTUS.  How  to  Wire  Buildings.  A  Manual  of  the  Art  of  Interior 
Wiring.  Fourth  Edition.  Illustrated.  12mo.,  cloth,  165  pp $1.50 

OHM,  G.  S.  The  Galvanic  Circuit  Investigated  Mathematically.  Berlin,  1827. 
Translated  by  William  Francis.  With  Preface  and  Notes  by  the  Editor, 
Thos.  D.  Lockwood.  Second  Edition.  Illustrated.  16mo.,  cloth,  269  pp. 
(No.  102  Van  Nostrand's  Science  Series.) 50  cents 

OLSSON,  ANDREW.  Motor  Control  as  used  in  Connection  with  Turret  Turning 
and  Gun  Elevating.  (The  Ward  Leonard  System.)  13  illustrations.  12mo., 
paper,  27  pp.  (U.  S.  Navy  Electrical  Series  No.  1.) Net,  .50 

OUDIN,  MAURICE  A.  Standard  Polyphase  Apparatus  and  Systems.  Illustrated 
with  many  Photo-reproductions,  Diagrams,  and  Tables.  Fifth  Edition,  revised. 
8vo.,  cloth,  369  pp Net,  $3.00 

PALAZ,  A.  Treatise  on  Industrial  Photometry.  Specially  applied  to  Electric 
Lighting.  Translated  from  the  French  by  G.  W.  Patterson,  Jr.,  Assistant 
Professor  of  Physics  in  the  University  of  Michigan,  and  M.  R.  Patterson, 
B.A.  Second  Edition.  Fully  Illustrated.  8vo.,  cloth,  324  pp $4.00 

PARR,  G.  D.  A.  Electrical  Engineering  Measuring  Instruments  for  Commercial 
and  Laboratory  Purposes.  Writh  370  Diagrams  and  Engravings.  8vo., 
cloth,  328  pp Net,  $3 .50 

PARSHALL,  H.  F.,  and  HOBART,  H.  M.  Armature  Windings  of  Electric  Machines. 
Third  Edition.  With  140  full-page  Plates,  65  Tables,  and  165  pages  of 
descriptive  letter-press.  4to.,  cloth,  300  pp $7 .50 

Electric    Railway    Engineering.     With  437  Figures  and  Diagrams  and  many 
Tables.     4to.,  cloth,  475  pp Net,  $10.00 

Electric   Machine   Design.     Being  a  revised  and  enlarged  edition  of  "Electric 
Generators."     648  Illustrations.     4to.,  half  morocco,  601  pp.  ..Net,  $12.50 


LIST  OF  WORKS  ON  ELECTRICAL  SCIENCE.  9 

PERRINE,  F.  A.  C.  Conductors  for  Electrical  Distribution :  Their  Manufacture 
and  Materials,  the  Calculation  of  Circuits,  Pole-Line  Construction,  Under- 
ground Working,  and  other  Uses.  Second  Edition.  Illustrated.  8vo., 
cloth,  287  pp Net,  $3.50 

POPE,  F.  L.  Modern  Practice  of  the  Electric  Telegraph.  A  Handbook  for  Elec- 
tricians and  Operators.  Seventeenth  Edition.  Illustrated.  8vo.,  cloth, 
234  pp $1 .50 

RAPHAEL,  F.  C.  Localization  of  Faults  in  Electric  Light  Mains.  Second  Edition, 
revised.  Illustrated.  Svo.,  cloth,  205  pp Net,  $3 . 00 

RAYMOND,  E.  B.  Alternating-Current  Engineering,  Practically  Treated.  Third 
Edition,  revised.  With  many  Figures  and  Diagrams.  8vo.,  cloth,  244  pp 

Net,  $2.50 

RICHARDSON,  S.  S.  Magnetism  and  Electricity  and  the  Principles  of  Electrical 
Measurement.  254  Illustrations.  12mo.,  cloth,  596  pp Net,  $2 .00 

ROBERTS,  J.  Laboratory  Work  in  Electrical  Engineering — Preliminary  Grade. 
A  series  of  laboratory  experiments  for  first  and  second-year  students  in 
electrical  engineering.  Illustrated  with  many  Diagrams.  8vo.,  cloth, 
218  pp Net,  $2 .00 

RUHMER,  ERNST.  Wireless  Telephony  in  Theory  and  Practice.  Translated 
from  the  German  by  James  Erskine-Murray.  Illustrated.  8vo.,  cloth, 
224  pp Net,  $3.50 

RUSSELL,  A.  The  Theory  of  Electric  Cables  and  Networks.  71  Illustrations. 
8vo.,  cloth,  275  pp Net,  $3.00 

SALOMONS,  DAVID.  Electric-Light  Installations.  A  Practical  Handbook.  Illus- 
trated. 12mo.,  cloth. 

Vol.  I.:    Management  of  Accumulators.     Ninth  Edition.     178  pp $2.50 

Vol.  II.:    Apparatus.     Seventh  Edition.     318  pp $2.25 

Vol.  III.:    Application.     Seventh  Edition.     234  pp $1 .50 

SEVER,  G.  F.  Electrical  Engineering  Experiments  and  Tests  on  Direct-Current 
Machinery.  Second  Edition,  enlarged.  With  Diagrams  and  Figures.  8vo., 
pamphlet,  75  pp Net,  $1 . 00 

and  TOWNSEND,  F.   Laboratory  and  Factory  Tests  in  Electrical  Engineering. 

Second  Edition.     Illustrated.     8vo.,  cloth,  269  pp Net,  $2 . 50 

SEWALL,  C.  H.  Wireless  Telegraphy.  With  Diagrams  and  Figures.  Second 

Edition,  corrected.  Illustrated .  8vo.,  cloth,  229  pp Net,  $2 . 00 

Lessons  in  Telegraphy.  Illustrated.  12mo.,  cloth,  104  pp Net,  $1 .00 

T.  Elements  of  Electrical  Engineering.  Third  Edition,  revised.  Illustrated. 

8vo.,  cloth,  444  pp $3.00 

The  Construction  of  Dynamos  (Alternating  and  Direct  Current).  A  Text- 
book for  students,  engineering  contractors,  and  electricians-in-charge. 
Illustrated.  8vo.,  cloth,  316  pp $3 .00 


10  LIST  OF  WORKS  ON  ELECTRICAL  SCIENCE. 

SHELDON,  S.,  and  HAUSMANN,  E.  Dynamo-Electric  Machinery :    Its  Construction, 

Design,  and  Operation. 
Vol.    I.:     Direct- Current  Machines.      Eighth     Edition,     completely    rewritten. 

Illustrated.     12mo.,  cloth,  281  pp Net,  $2 . 50 

Vol.  II.:     Alternating-Current  Machines:     Eighth   Edition,    rewritten.     12mo., 

cloth,  353  pp Net,  $2.50 

Electric  Traction  and  Transmission  Engineering.     127  illustration.      12mo., 

cloth.     317   pp Net,  $2 .50 

SLOANE,  T.  O'CONOR.     Standard  Electrical  Dictionary.     300  Illustrations.     12mo., 

cloth,  682  pp $3.00 

Elementary  Electrical  Calculations.  A  Manual  of  Simple  Engineering 
Mathematics,  covering  the  whole  field  of  Direct  Current  Calculations,  the 
basis  of  Alternating  Current  Mathematics,  Networks,  and  typical  cases  of 
Circuits,  with  Appendices  on  special  subject.  8vo.,  cloth.  Illustrated. 
304  pp Net,  $2 .00 

SNELL,  ALBION  T.  Electric  Motive  Power.  The  Transmission  and  Distribution 
of  Electric  Power  by  Continuous  and  Alternating  Currents.  With  a  Section 
on  the  Applications  of  Electricity  to  Mining  Work.  Second  Edition. 
Illustrated.  8vo.,  cloth,  411  pp Net,  $4.00 

SODDY,  F.  Radio-Activity ;  an  Elementary  Treatise  from  the  Standpoint  of  the 
Disintegration  Theory.  Fully  Illustrated.  8vo., cloth,  214  pp.  .Net,  $3.00 

SOLOMON,  MAURICE.  Electric  Lamps.  Illustrated.  8vo.,  cloth.  (Van  Nos- 
trand's  Westminster  Series.) Net,  $2 .00 

STEWART,  A.  Modern  Polyphase  Machinery.  Illustrated.  12mo.,  cloth,  296 
pp Net,  $2 .00 

SWINBURNE,  JAS.,  and  WORDINGHAM,  C.  H.  The  Measurement  of  Electric 
Currents.  Electrical  Measuring  Instruments.  Meters  for  Electrical  Energy. 
Edited,  with  Preface,  by  T.  Commerford  Martin.  Folding  Plate  and  Numer- 
ous Illustrations.  16mo.,  cloth,  241  pp.  (No.  109  Van  Nostrand's  Science 
Series.) 50  cents 

SWOOPE,  C.  WALTON.  Lessons  in  Practical  Electricity:  Principles,  Experi- 
ments, and  Arithmetical  Problems.  An  Elementary  Text-book.  Eleventh 
Edition,  enlarged  with  a  chapter  on  alternating  currents.  404  illustrations. 
12mo.,  cloth,  507  pp Net,  $2 . 00 

THIESS,  J.  B.  and  JOY,  G.  A.  Toll  Telephone  Practice.  268  illustrations.  8vo. 
cloth,  about  400  pp In  Press 

THOM,  C.,  and  JONES,  W.  H.  Telegraphic  Connections,  embracing  recent  methods 
in  Quadruplex  Telegraphy.  20  Colored  Plates.  8vo.,  cloth,  59  pp.  .$1.50 

THOMPSON,  S.  P.,  Prof.  Dynamo-Electric  Machinery.  With  an  Introduction 
and  Notes  by  Frank  L.  Pope  and  H.  R.  Butler.  Fully  Illustrated.  16mo., 

cloth,  214  pp.     (No.  66  Van  Nostrand's  Science  Series.) 50  cents 

Recent  Progress  in  Dynamo-Electric  Machines.  Being  a  Supplement  to 
"Dynamo-Electric  Machinery."  Illustrated.  16mo.,  cloth,  113  pp.  (No. 
75  Van  Nostrand's  Science  Series.) 50  cents 


LIST  OF   WORKS   ON  ELECTRICAL   SCIENCE.  11 

TOWNSEND,  FITZHUGH.  Alternating  Current  Engineering.  Illustrated.  8vo., 
paper,  32  pp Net,  75  cents 

UNDERBILL,  C.  R.  Solenoids,  Electromagnets  and  Electromagnetic  Windings. 
218  Illustrations.  12mo.,  cloth,  345  pp Net,  $2 .00 

URQUHART,  J.  W.  Dynamo  Construction.  A  Practical  Handbook  for  the  use 
of  Engineer  Constructors  and  Electricians  in  Charge.  Illustrated.  12mo., 
cloth $3.00 

Electric  Ship-Lighting.     A  Handbook  on  the  Practical  Fitting  and  Running  of 

Ship's  Electrical  Plant,  for  the  use  of  Ship  Owners  and  Builders,   Marine 

.Electricians,  and  Sea-going  Engineers  in  Charge.   88  Illustrations.   12mo., 

cloth,  303  pp $3.00 

Electric-Light  Fitting.  A  Handbook  for  Working  Electrical  Engineers,  em- 
bodying Practical  Notes  on  Installation  Management.  Second  Edition, 
with  numerous  Illustrations.  12mo.,  cloth $2.00 

Electroplating.     Fifth  Edition.     Illustrated.     12mo.,  cloth,  230  pp $2.00 

Electrotyping.     Illustrated.     12mo.,  cloth,  228  pp $2.00 

WADE,  E.  J.  Secondary  Batteries:  Their  Theory,  Construction,  and  Use.  Second 
Edition,  corrected.  265  Illustrations.  8vo.,  cloth,  501  pp Net,  $4.00 

WADS  WORTH,  C.     Electric  Battery  Ignition.     20  Illustrations.     16mo.     paper. 

In  Press 

WALKER,  FREDERICK.  Practical  Dynamo-Building  for  Amateurs.  How  to 
Wind  for  any  Output.  Third  Edition.  Illustrated.  16mo.,  cloth,  104  pp. 
(No.  98  Van  Nostrand's  Science  Series.) 50  cents 

SYDNEY  F.     Electricity  in  Homes  and  Workshops.     A  Practical  Treatise  on 

Auxiliary    Electrical    Apparatus.     Fourth    Edition.      Illustrated.       12mo., 

cloth,  358  pp $2 .00 

Electricity  in  Mining.     Illustrated.     8vo.,  cloth,  385  pp $3.50 

WALLING,  B.  T.,  Lieut.-Com.  U.S.N.,  and  MARTIN,  JULIUS.  Electrical  Installa- 
tions of  the  United  States  Navy.  With  many  Diagrams  and  Engravings. 
8vo.,  cloth,  648  pp $6.00 

WATT,  ALEXANDER.      Electroplating  and  Refining  of  Metals.       New   Edition, 

rewritten  by  Arnold  Philip.     Illustrated.     8vo.,  cloth,  704  pp.  .Net,  $4.50 

Electro -metallurgy.    Fifteenth  Edition.    Illustrated.    12mo.,  cloth,  225  pp.  .$1 .00 

WEBB,  H.  L.  A  Practical  Guide  to  the  Testing  of  Insulated  Wires  and  Cables. 
Fifth  Edition.  Illustrated.  12mo.,  cloth.,  118  pp $1 . 00 

WEEKS,  R.  W.     The  Design  of   Alternate-Current  Transformer.      New  Edition 

in  Press 


12  LIST  OF  WORKS  ON  ELECTRICAL  SCIENCE. 

WEYMOUTH,  F.  MARTEN.  Drum  Armatures  and  Commutators.  (Theory  and 
Practice.)  A  complete  treatise  on  the  theory  and  construction  of  drum- 
winding,  and  of  commutators  for  closed-coil  armatures,  together  with  a  full 
resume  of  some  of  the  principal  points  involved  in  their  design,  and  an 
exposition  of  armature  reactions  and  sparking.  Illustrated.  8vo.,  cloth, 
295 pp Net,  $3.00 

WILKINSON,  H.  D.  Submarine  Cable-Laying,  Repairing,  and  Testing.  New  Edition. 
Illustrated.  8vo.,  cloth In  Press 

YOUNG,  J.  ELTON.  Electrical  Testing  for  Telegraph  Engineers.  Illustrated. 
8vo.,  cloth,  264  pp Net,  $4.00 

ZEIDLER,  J.  and  LUSTGARTEN,  J.  Electric  Arc  Lamps.  Their  principles,  con- 
struction and  working.  160  illustrations.  8vo.,  cloth,  200  pp Net,  $2.00 


96=page  Catalog  of  Books  on  Electricity,  classified  by 
subjects,  will  be  furnished  gratis,  postage  prepaid,  on 
application. 


RETURN  TO  the  circulation  desk  of  any 
University  of  California  Library 
or  to  the 

NORTHERN  REGIONAL  LIBRARY  FACILITY 
Bldg.  400,  Richmond  Field  Station 
University  of  California 
Richmond,  CA  94804-4698 

ALL  BOOKS  MAY  BE  RECALLED  AFTER  7  DAYS 

•  2-month  loans  may  be  renewed  by  callina 
(510)642-6753 

•  1-year  loans  may  be  recharged  by  brinqinq 
books  to  NRLF 

•  Renewals  and  recharges  may  be  made 
4  days  prior  to  due  date 

DUE  AS  STAMPED  BELOW 


DD20  6M  9-03 


749202 


? 


UNIVERSITY  OF  CALIFORNIA  LIBRARY 


